95 replies to this topic

[stinger]

I was filing in some deep scratches with west epoxy mixed with cabosil. It's been about 18 hrs, above 7 Celsius and I was hoping to start sanding. But the epoxy doesn't seem to have fully cured. It is still tacky and gummy yet hard. I've never seen this. I use the pumps supplied with new resin and 205 hardener. It did cool off to about 7 over night but when I left the job site yesterday? The epoxy had at least 3 hours around 15 Celsius. Help

[tikipete]

I was filing in some deep scratches with west epoxy mixed with cabosil. It's been about 18 hrs, above 7 Celsius and I was hoping to start sanding. But the epoxy doesn't seem to have fully cured. It is still tacky and gummy yet hard. I've never seen this. I use the pumps supplied with new resin and 205 hardener. It did cool off to about 7 over night but when I left the job site yesterday? The epoxy had at least 3 hours around 15 Celsius. Help

You can heat it, that might help but there is always risk with adding heat. If it's structural I wouldn't trust it! Dig it out and start over. Try Foggies "hot water bag"! http://forums.sailin...howtopic=133855 but read the whole thread first.

[stinger]

Or am I not being patient enough? It seems the thin coats are fine but the thicker ones aren't.

[tikipete]

I'm not sure. I'd hold off and talk to WEST on Monday but I'm guessing the ratio is off.

[Oxygen Mask]

There's probably nothing wrong.
You need TIME and HEAT.

I've been building stuff with epoxy for 15+ years. I've used 5 or 6 brands, major and discount stuff.
Even in the heat of summer, I have never had any epoxy cured enough to sand in 18 hours.

Also, you need heat. At 7c (44F) the epoxy really won't cure much, at 15c it's only barely curing. It will cure hard enough to sand at 15c but it will take a couple days.

I find that if I want sanding to go easier and not clog up lots of paper, don't rush it. Let it FULLY cure- at least 2-3 days, and it makes nice dust and sands easier.

[Jim Conlin]

Patience.
Gentle warmth from a heat lamp or an electric blanket will help.
Not over 100F (40C).

If it hasn't cured after 12 hrs at 100F, it's off-ratio and should be removed.

[12 metre]

It could be due to impoper an improper mix ratio, but I've found that epoxy is pretty forgiving as far as mix ratio goes - compared to polyester anyway. I once mixed some System 3 at 3:1 rather than 2:1 - it turned out fine but took quite a bit longer to cure.

My guess is the problem is temperature related. 3 hrs at 15c isn't much and with the temp dipping down to 7c, that would slow the curing process down to a crawl, even with the 205, which West recommends to use at temps above 10c. Applying some heat (not a heat gun or anything extreme) should get the curing process going again. It will cure eventually as the weather gets warmer.

[P2 Marine]

If it's tacky and hard it has probably cured, and the tackiness could be just an amine blush, which is common with West when it cures. Try a little soap and water with a scrubby sponge and if it is a blush that will get rid of the tackiness and you'll be ready to sand.

Cheers,
Rob

[-Julian-]

I was painting with an epoxy paint on thursday, and it will stay uncured for days in the fridge. 7º C is not much warmer... I would leave it another day, hopefully it gets sunny tomorrow.

[stinger]

Thanks all for your replies. Looks like I was impatient. THe epoxy hardened quite a bit over the last few hours in the sun light.

[simbert]

use cold cure next time

[casc27]

If it's tacky and hard it has probably cured, and the tackiness could be just an amine blush, which is common with West when it cures. Try a little soap and water with a scrubby sponge and if it is a blush that will get rid of the tackiness and you'll be ready to sand.

Cheers,
Rob

Amine blush is not tacky, more waxy or greasy. Partially cured epoxy is tacky. Give it more time and temperature and you will likely be fine.

[P2 Marine]

If it's tacky and hard it has probably cured, and the tackiness could be just an amine blush, which is common with West when it cures. Try a little soap and water with a scrubby sponge and if it is a blush that will get rid of the tackiness and you'll be ready to sand.

Cheers,
Rob

Amine blush is not tacky, more waxy or greasy. Partially cured epoxy is tacky. Give it more time and temperature and you will likely be fine.

Waxy, greasy, tacky, sticky. Semantics...Scratches should be faired out with 410 microbaloons not cabosil. I suspect a hot mix that blushed.

Cheers,
Rob

[stinger]

If it's tacky and hard it has probably cured, and the tackiness could be just an amine blush, which is common with West when it cures. Try a little soap and water with a scrubby sponge and if it is a blush that will get rid of the tackiness and you'll be ready to sand.

Cheers,
Rob

Amine blush is not tacky, more waxy or greasy. Partially cured epoxy is tacky. Give it more time and temperature and you will likely be fine.

Waxy, greasy, tacky, sticky. Semantics...Scratches should be faired out with 410 microbaloons not cabosil. I suspect a hot mix that blushed.

Cheers,
Ron

Can you describe "a hot mix that blushed"? I used cabosil to give it a try. I figured I would give cabosil a try on a small job.

[Ishmael]

If it's tacky and hard it has probably cured, and the tackiness could be just an amine blush, which is common with West when it cures. Try a little soap and water with a scrubby sponge and if it is a blush that will get rid of the tackiness and you'll be ready to sand.

Cheers,
Rob

Amine blush is not tacky, more waxy or greasy. Partially cured epoxy is tacky. Give it more time and temperature and you will likely be fine.

Waxy, greasy, tacky, sticky. Semantics...Scratches should be faired out with 410 microbaloons not cabosil. I suspect a hot mix that blushed.

Cheers,
Ron

Can you describe "a hot mix that blushed"? I used cabosil to give it a try. I figured I would give cabosil a try on a small job.

When I Googled hot minx that blushed I came up with this:



Don't you think they should have used a live person to be the model?

[Oxygen Mask]

I used cabosil to give it a try. I figured I would give cabosil a try on a small job.

Use a hard backing plate/block (not a soft spongy one) when you sand, good quality sharp sandpaper (change often,) and patience, or you may end up with a "high point in a hollow." (The cabosil mix will be VERY hard, it's like granite...)

[casc27]

Not semantics at all. The words have distinctly different meanings. If you are going to work with these materials you need to be able to discern the difference between the tacky/sticky surface of something not fully cured and the waxy/greasy/unctuous feel of a fully cured surface with an amine blush on it. For those who need a reference:

Tacky

Sticky

Greasy

Waxy

If it's tacky and hard it has probably cured, and the tackiness could be just an amine blush, which is common with West when it cures. Try a little soap and water with a scrubby sponge and if it is a blush that will get rid of the tackiness and you'll be ready to sand.

Cheers,
Rob

Amine blush is not tacky, more waxy or greasy. Partially cured epoxy is tacky. Give it more time and temperature and you will likely be fine.

Waxy, greasy, tacky, sticky. Semantics...Scratches should be faired out with 410 microbaloons not cabosil. I suspect a hot mix that blushed.

Cheers,
Rob

[tikipete]

somewhere along the line I read not to work a less than 60⁰ F.

[Cavelamb]

somewhere along the line I read not to work a less than 60⁰ F.

7 C is what, 44 in real degrees?

So that's the first issue.

Second is the mix ratio.

For small batches the pumps can be way off.
I don't even think of using pumps until you need a cup of epoxy (or more)

Much better control of the mix ratio can be obtained from syringes - vetinary supply stores sell several sizes.
Get a set that matches the ratio for the hardener that you want to use.
For 5:1 get a 30cc and 5cc.
For 3:1 get a 60cc and a 20cc

To fill them, first decant some juice into smaller containers. Epoxy in one, hardener in another.
Then use those to pour juice into the syringe from the back end).
Trying to suck cool epoxy into the syringe by pulling the plunger will just roll the rubber tip off of the plunger.

I simply fold a paper towel or napkin and use that to block the tip while filling.

Then stand the filled syringe in a can or cup (tip up) until needed.
One for epoxy, one for catalyst.

When doing (slightly) larger jobs I may fill two or three syringes at a time
That way when a fresh mix is needed, just squirt juices and mix.
Quick and simple.

YMMV, of course.
But that's my way.


Richard

[Cavelamb]

I was filing in some deep scratches with west epoxy mixed with cabosil. It's been about 18 hrs, above 7 Celsius and I was hoping to start sanding. But the epoxy doesn't seem to have fully cured. It is still tacky and gummy yet hard. I've never seen this. I use the pumps supplied with new resin and 205 hardener. It did cool off to about 7 over night but when I left the job site yesterday? The epoxy had at least 3 hours around 15 Celsius. Help

One other thought...

Try MarineTex epoxy for this kind of thing - deep scratches, gouges, old screw holes, etc...

Get the white stuff - and use regular gelcoat pigments (available at West Marine) to match colors.

It works beautifully! Sticks tenaciously, sands easily and buffs out to a great shine.

Good stuff, Maynard.

[dreaded]

For small batches the pumps can be way off.
I don't even think of using pumps until you need a cup of epoxy (or more)

Much better control of the mix ratio can be obtained from syringes - vetinary supply stores sell several sizes.
Get a set that matches the ratio for the hardener that you want to use.
For 5:1 get a 30cc and 5cc.
For 3:1 get a 60cc and a 20cc

To fill them, first decant some juice into smaller containers. Epoxy in one, hardener in another.
Then use those to pour juice into the syringe from the back end).
Trying to suck cool epoxy into the syringe by pulling the plunger will just roll the rubber tip off of the plunger.

I simply fold a paper towel or napkin and use that to block the tip while filling.

Then stand the filled syringe in a can or cup (tip up) until needed.
One for epoxy, one for catalyst.

When doing (slightly) larger jobs I may fill two or three syringes at a time
That way when a fresh mix is needed, just squirt juices and mix.
Quick and simple.

YMMV, of course.
But that's my way.


Richard

Cool .. thanks for the tip... anytime you want to come to WRL to help fix, you're more than welcome..

[xyzzy]

For small batches the pumps can be way off.
I don't even think of using pumps until you need a cup of epoxy (or more)

Much better control of the mix ratio can be obtained from syringes - vetinary supply stores sell several sizes.
Get a set that matches the ratio for the hardener that you want to use.
For 5:1 get a 30cc and 5cc.
For 3:1 get a 60cc and a 20cc

I got one of these scales for mixing small amounts of epoxy. http://www.harborfre...cale-97920.html
You can just slowly pump some out into the mixing cup until the weight is right. Helps to have a calculator since the mixing ratio by weight isn't nice and even like the volume ratio.

[Ultraman]

For small batches the pumps can be way off.
I don't even think of using pumps until you need a cup of epoxy (or more)

Much better control of the mix ratio can be obtained from syringes - vetinary supply stores sell several sizes.
Get a set that matches the ratio for the hardener that you want to use.
For 5:1 get a 30cc and 5cc.
For 3:1 get a 60cc and a 20cc

I got one of these scales for mixing small amounts of epoxy. http://www.harborfre...cale-97920.html
You can just slowly pump some out into the mixing cup until the weight is right. Helps to have a calculator since the mixing ratio by weight isn't nice and even like the volume ratio.

And you can use the digital scale for all your other weighing needs...

[Oxygen Mask]

Much better control of the mix ratio can be obtained from syringes - vetinary supply stores sell several sizes.

Yep, that's what I use. Dental supply syringes are great for really small batches.

[TQA]

One other thing.



If you mix the filler with the resin before adding the hardner I have had some batches never set hard just go to toffee.

[Oxygen Mask]

I have never mixed it that way, I always make sure I mix the epoxy thoroghly first since that mix is critical. (A reason NOT to put all the stuff in a baggie and trust that squishing it around will mix it properly.)

BUT - someone sells ready to mix filleting blend (I had some years back, don't recall what brand it was) that had the fillers premixed. One tub was a brownish stiff putty, the other tub contained a whitish goo - looked like vaseline. It was great stuff for small batches, easy to mix with a spatula. So it's possible.

[Ishmael]

I have never mixed it that way, I always make sure I mix the epoxy thoroghly first since that mix is critical. (A reason NOT to put all the stuff in a baggie and trust that squishing it around will mix it properly.)

BUT - someone sells ready to mix filleting blend (I had some years back, don't recall what brand it was) that had the fillers premixed. One tub was a brownish stiff putty, the other tub contained a whitish goo - looked like vaseline. It was great stuff for small batches, easy to mix with a spatula. So it's possible.

Possibly System 3.

http://www.systemthr...uikFair-c17.htm

[casc27]

Now that's interesting. I've never mixed that way. (And now I'm glad I haven't.) I wonder if Vegas or one of the other gurus has any insight on any issues mixing the filler and resin before adding the hardener.

One other thing.



If you mix the filler with the resin before adding the hardner I have had some batches never set hard just go to toffee.

[Rohanoz]

I premix the fillers with polyester every time - no issues.

Epoxy on the other hand... not sure how it would work given the ratios - a couple of % vs 2/3/4-1 is a different kettle of fish!

[Cavelamb]

Read the directions. Mom always made me anyway.

[mad]

Now that's interesting. I've never mixed that way. (And now I'm glad I haven't.) I wonder if Vegas or one of the other gurus has any insight on any issues mixing the filler and resin before adding the hardener.

One other thing.



If you mix the filler with the resin before adding the hardner I have had some batches never set hard just go to toffee.

Mixing fillers into epoxy resin without hardener is not really a good idea. You will only end up having to add more filler additive after you have added the hardener as you will have the wrong consistency otherwise, plus people sometimes forget and put resin and filler mix back on the scales and adjust hardener ratio to suit overall weight.

No issues with adding fillers to polyester and then catalyzing though.

Edit
Having posted the above I can remember hearing about mixing Cabosil into epoxy 12 hrs before use and then adding hardener for use, but its was a specialised process and can't really remember what it was.

[simbert]

somewhere along the line I read not to work a less than 60⁰ F.

7 C is what, 44 in real degrees?

So that's the first issue.

Second is the mix ratio.

For small batches the pumps can be way off.
I don't even think of using pumps until you need a cup of epoxy (or more)

Much better control of the mix ratio can be obtained from syringes - vetinary supply stores sell several sizes.
Get a set that matches the ratio for the hardener that you want to use.
For 5:1 get a 30cc and 5cc.
For 3:1 get a 60cc and a 20cc

To fill them, first decant some juice into smaller containers. Epoxy in one, hardener in another.
Then use those to pour juice into the syringe from the back end).
Trying to suck cool epoxy into the syringe by pulling the plunger will just roll the rubber tip off of the plunger.

I simply fold a paper towel or napkin and use that to block the tip while filling.

Then stand the filled syringe in a can or cup (tip up) until needed.
One for epoxy, one for catalyst.

When doing (slightly) larger jobs I may fill two or three syringes at a time
That way when a fresh mix is needed, just squirt juices and mix.
Quick and simple.

YMMV, of course.
But that's my way.


Richard

Use a 7 bucks kitchen scale, put the cup on the scale, zero it, pump both parts in accordingly. Forget about syringes, sticky as hell.
http://www.amazon.com/Weigh-MS-500-BLK-Digital-Pocket-Scale/dp/B000P1NYE8/ref=sr_1_4?s=kitchen&ie=UTF8&qid=1334686412&sr=1-4

[_Vegas_]

Mixing filled resin systems is a little tricky but obvious doable with epoxy - the problem inherent is the viscosity differentials. If you have a thick resin and a thin hardener you end up mixing your brains out to achieve a homogenous solution - and the chances of off ratio parts of the thickened mixture is increased. Now if your hardener and resin were both already thickened with your filler then you have a better chance of homogeneity, but if you go that far, might as well mix the resin and hardener and then add your filler (less process steps to success).

[Oxygen Mask]

I premix the fillers with polyester every time - no issues.

Epoxy on the other hand... not sure how it would work given the ratios - a couple of % vs 2/3/4-1 is a different kettle of fish!

Although the ratios are more critical for epoxy than for poly, the thing that most people don't 'get' is that even though we commonly call the 2 parts 'resin' and 'hardener', they really are neither. They are just 2 parts of the whole, that won't form epoxy until mixed. Part A isn't a resin at all, and Part B isn't a hardener (in the sense of the catalyst in a polyester system,) it's the remainder of the chemicals needed to create epoxy. This is why the correct ratio and a thorough mix is so critical.

[tikipete]

My memory is not what it was. But, iirc, pre-mixing additives before adding hardener can cause a fire and even an explosion. Anyone have a cite? I've no idea where I read that. Or if...

[casc27]

My memory is not what it was. But, iirc, pre-mixing additives before adding hardener can cause a fire and even an explosion. Anyone have a cite? I've no idea where I read that. Or if...

Um, I think that is when you are making c-4, not mixing boat building resins.

[_Vegas_]

My memory is not what it was. But, iirc, pre-mixing additives before adding hardener can cause a fire and even an explosion. Anyone have a cite? I've no idea where I read that. Or if...

If you are using a low molecular weight amine curing system, the rate of reaction can be very quick that the exothermal energy created could ignite the container or the materials themselves if contained in a large enough mass.

pre-filled resin and hardener systems are nothing new - There are a ton on the market that are used everyday with great success - For the WEST System line of products, the Six10 (610) is a thickened 2-part system that mixes through a static mixing apparatus and I've never heard of it catching on fire or blowing up.

Now with Polyester , if you have an over promoted poly resin (too much cobalt) and add too much MEKP - you can get a boom or a fire.

[dreaded]

back to syringes, how thick a mixture can you use in a syringe?

[mad]

My memory is not what it was. But, iirc, pre-mixing additives before adding hardener can cause a fire and even an explosion. Anyone have a cite? I've no idea where I read that. Or if...

If you are using a low molecular weight amine curing system, the rate of reaction can be very quick that the exothermal energy created could ignite the container or the materials themselves if contained in a large enough mass.

pre-filled resin and hardener systems are nothing new - There are a ton on the market that are used everyday with great success - For the WEST System line of products, the Six10 (610) is a thickened 2-part system that mixes through a static mixing apparatus and I've never heard of it catching on fire or blowing up.

Now with Polyester , if you have an over promoted poly resin (too much cobalt) and add too much MEKP - you can get a boom or a fire.

For more fun just mix the MEKP with the cobalt and leave out the resin

back to syringes, how thick a mixture can you use in a syringe?

not very thick at all

[Oxygen Mask]

back to syringes, how thick a mixture can you use in a syringe?

As thick as you can press through it? As thick as the nozzle end will apply? Depends on the syringe. (depends on the additives too, some have a 'chunkiness' that clogs syringes...)

[mr_fabulous]

I'm not sure. I'd hold off and talk to WEST on Monday but I'm guessing the ratio is off.

+1. If you are not familiar with epoxy, too much hardner = gummy cure.

[mad]

I give up, some people should just stick to water based/single pack adhesives.

[JumpingJax]

I give up, some people should just stick to water based/single pack adhesives.

Or even (heaven forfend) read the directions. West Systems has GREAT information on-line that would prevent most questions of this sort if folks would just take the trouble to look 'em up and follow directions.

[fastyacht]

I premix the fillers with polyester every time - no issues.

Epoxy on the other hand... not sure how it would work given the ratios - a couple of % vs 2/3/4-1 is a different kettle of fish!

Although the ratios are more critical for epoxy than for poly, the thing that most people don't 'get' is that even though we commonly call the 2 parts 'resin' and 'hardener', they really are neither. They are just 2 parts of the whole, that won't form epoxy until mixed. Part A isn't a resin at all, and Part B isn't a hardener (in the sense of the catalyst in a polyester system,) it's the remainder of the chemicals needed to create epoxy. This is why the correct ratio and a thorough mix is so critical.

Actually, epoxies commonly used in boatbuilding are "epoxy resin" and "amine hardener". That is what they are: epichlorohydrin / bisphenol A based epoxy, reacted with a tetrafunctional or other appropriately multifunctional amine.

Polyester is not actually "catalyzed" by the MEKP. Rather, it is "initiated". The MEKP is not a catalyst. Rather, it eats up the inhibitor chemicals which are mixed into the unsaturated polyester to prevent it going off spontaneously. (I will add that polyester resin by itself will not react fast enough to do anything useful; therefore it has a metal salt promoter added to it, e.g. cobalt napthenate.) When you buy resin, you should pay attention to whether it is "promoted" resin or not. Some are not prepromoted because it (obviouslty) shortens the shelf live. An example is the highly filled tooling resin systems--often these are neat, with no thixotropoy, and no promoter. You have to first mix in the promoter, then blend in the ATH filler, then later that day when you make your tool, initiate with MEKP in the normal way.

Further, I will add that the ratios in epoxy are quite critical. Some more than others, but you never want to be more than a few percent off. Also note that the ratio by *weight* is not equal to the ratio by *volume* and you should read the literature for the specifics!

Polyester is initiated and the amount of initiator can vary by as much as 2:1 or more--in other words a minimum of 0.75% and a maximum of 2% is fairly typical. The choice is made by temperature, batch size, casting thickness and desired open time.

[fastyacht]

If you are filling gouges in a polyester boat, it is much quicker to use a styrenated resin system, either polyester, or if you are anal about it or your boat is better than ortho poly, use a vinylester or an isopthalic polyester as appropriate. Styrenated systems are much faster to cure.

However, the styrenated systems will not cure properly below room temperature. Heat lamps are very tricky because they put out an unknown amount of energy and you can easily cook a polyester patch. A better approach is to make a simple tent, with a nonflammable material, and put a light bulb inside with a thermometer. If you get the temp over 65 you are ok.

Epoxy is slower to cure, always, and gelcoat doesn't stick to it. However in cold temperatures it is actually easier to use than the styrenateds because it will cure even when cold--it just takes longer. "Cold Cure" brand is sold for this but even ordinary West 105/205 will cure even below freezing--just takes weeks! Just remember, however, that it will "post cure" when the temperature rises later. (This is what causes "print-through" and why dark boats get it worse than light boats--they get hotter and post cure more). Let's say you do an epoxy repair with 10oz cloth and it cures in 40F conditions, and you sand it and briefly warm it and then paint it. You are likely to see the weave next summer, when it finally cures out "fully" to the summer temperature.

If you want to be competent with resins, RTFM41. Seriously. There is some good advice in this thread, interspersed with some very inaccurate statements.

[Mr. Fixit's brother,, Mr. Fixit]

Good job Fastyacht. +1.. another thing to note...stick to pre-promoted and leave mixing unpromoted polyester resins to the pro's. Getting that wrong can cause pretty toxic fires.

[_Vegas_]

If you are filling gouges in a polyester boat, it is much quicker to use a styrenated resin system, either polyester, or if you are anal about it or your boat is better than ortho poly, use a vinylester or an isopthalic polyester as appropriate. Styrenated systems are much faster to cure.

However, the styrenated systems will not cure properly below room temperature. Heat lamps are very tricky because they put out an unknown amount of energy and you can easily cook a polyester patch. A better approach is to make a simple tent, with a nonflammable material, and put a light bulb inside with a thermometer. If you get the temp over 65 you are ok.

Epoxy is slower to cure, always, and gelcoat doesn't stick to it. However in cold temperatures it is actually easier to use than the styrenateds because it will cure even when cold--it just takes longer. "Cold Cure" brand is sold for this but even ordinary West 105/205 will cure even below freezing--just takes weeks! Just remember, however, that it will "post cure" when the temperature rises later. (This is what causes "print-through" and why dark boats get it worse than light boats--they get hotter and post cure more). Let's say you do an epoxy repair with 10oz cloth and it cures in 40F conditions, and you sand it and briefly warm it and then paint it. You are likely to see the weave next summer, when it finally cures out "fully" to the summer temperature.

If you want to be competent with resins, RTFM41. Seriously. There is some good advice in this thread, interspersed with some very inaccurate statements.

I do not agree with this statement - polyester gelcoat does indeed bond to epoxy substrate if properly prepared - The bond is mechanical, whereby the epoxy substrate is sanded and the gelcoat keys in to the epoxy. While most epoxies used in boat building are high solids, and subsequently have low or no VOC's to outgas - the shrinkage factor is highly reduced. Whereas polyester with outgas and shrink (some to almost 10%) - So why does a 100' polyester boat not come out of the mold as a 90'er? The material goes into tension...we've all seen a small crack in gelcoat run and spider web out - this is a function of the gelcoat being in tension over its substrate - While epoxies will expand and contract with thier co-joined materials (2-6%) - If the epoxy is moving under the gelcoat and there is not a good mechanical bond, I can see the gelcoat cracking - of course there are flex additives one can add to the gelcoat to help with this. Think about the Carol Marine Farr 40's ...

[fastyacht]

Which makes more sense? Repair a polyester boat, using polyester laminating resin or unwaxed fairing putty, followed by polyester gelcoat, or, repairing a polyester boat with epoxy, waiting 2 weeks, sanding the epoxy, applying polyester gelcoat?

If there is concern about adhesion in the polyester situation (polyesters don't have as good secondary bonding as epoxy) then you use a vinylester repair material. Vinylester is essentially a styrenated epoxide. You get the convenience of compatibility with polyesters, a convenient open primary bond window after gel, and superior adhesion to previously cured surfaces.

Hmmmmm....gee, such a difficult decision! :-/

Gougeon has done an extraordinary job of marketing. But falling into "I epoxy everything" causes more trouble than it solves.

[_Vegas_]

Of course there is no blanket solution to every problem - In cases poly or vinyl is the way to go - in other cases epoxy. I'm a big fan of Methylmethacrylates too- aside from the smell, limited surface prep and a fast bond - what's not to like? Decay of tensile elongation over time is one - but hey nothing is perfect.

If one is engaged in a non structural repair of a poly boat, by all means use poly resin - if it is structural, something with a better interfacial connection (secondary bond) like vinyl or epoxy may be more suitable - and if it is below the waterline, mositure exclusion effectiveness is alwasy a concern.

And far as Gougeon marketing goes - why wouldn't a company that makes epoxy, keep coming up with applications for its product's use while supplying sound scientific data to support thier claims based on ASTM test methods?

I'm not here to start a shit fight or a Jihad over "my glue is better than your glue" - the long and short is , use the right product for the job and be informed of the available options.

[fastyacht]

BisA/Amine epoxy "moisture exclusion" is laughable.

It is pretty hard to find a case where a polyester boat cannot be properly repaired--structurally--with the same resin it was built with. Adequate scarf slope takes care of that.

The "epoxy sticks better" campaign makes me laugh, because most of the time when you look at fiberglass "structural" repairs carried out by amateurs or hacks, they are completely stupid. They *need* all the help they can get--because they are so poorly planned, designed and executed. For instance, 8:1 slope on a bottom repair. See this all the time. Of *course* you need epoxy to make that work! It may still fail!

Do repairs properly, and a polyester boat repaired with polyester will do great. Do however be mindful of which "polyester." If it was DCPD, for instance, or Vinylester, ordinary ortho is a step down and you won't be matching.

And to your point about resin properties and shrink, a repair that doesn't match the original will be subject to interfacial stresses due to property mismatch. Remember, in the end, all the loads go into and out of the repair through a secondary bond line. If this is in anything but shear, you will be in trouble.

[_Vegas_]

Go ahead and make your secondary bonds to cured DCPD with DCPD - don't forget to send the insurance company pics too. The secondary bond of DCPD to itself is well documented as shitty. Seeing as it is almost Christmas, may I send you a copy of the Composites Engineering Handbook? You may find Chapter three (3) and eye opener on the subject of Matrix Resins and Fiber/Matrix Adhesion.

And for the record the author Thomas Juska worked at the Naval Surface Warfare Center - not West System

[fastyacht]

Did I tell you to use DCPD to bond to DCPD? Nope. I said to pay attention to what your original laminate is made of...in my example, not using Ortho to fix all non-epoxy laminates.

Composites repair isn't a bubble-gum and bailing wire garage activity, if you want it to work. I think we agree there :-)

Oh, and sure, I'd love an extra copy--you are a generous person-that's about $300!

[Soñadora]

this thread is like a boatbuilders version of Breaking Bad.

Fastyacht, thanks for the chemistry lesson. Pretty interesting stuff. It makes me wonder how any of us numbskulls are able to do anything with "epoxy". You mentioned that the mix is critical, however there must be some tolerance for getting it wrong. God knows I've gotten it wrong many times. I'm sure I'm not the only one who has experienced an air bubble in the plunger. Then you try to compensate by squirting out what you think was the amount you missed.

Regarding the OP, last winter I did quite a bit of epoxying here in the frozen wasteland (actually pretty mild last winter with temps in the 20s - 30s). One particular piece I epoxied took a week to cure. Contrast to this summer where we had record breaking heat and inside my enclosure temps were above 120. I could epoxy a piece with fast cure in the morning and be sanding by afternoon. Had to work FAST and in small batches. More than once I made too big a batch and the cup I was using to mix in just about caught on fire.

[Rasputin22]

Had a buddy who was going to tab in the main bulkhead of his sloop as it was just sitting in a molded channel in the interior molding. You could see it shift when sailing so he bit the bullet and cut the flanges of the channel away and prepped to bond directly to the hull skin. An insane amount of work, especially since he and his wife and daughter were full time live aboards. With plenty of professional advice from the boatbuilders and laminators in the anchorage, he had everything prepped for the big day and the lamination. It was his 6 year old daughters birthday and his wife had a full day of beach party activities for her and about 20 of her friends so he dropped the ladies off at the beach and dinghied back to the boat and rolled up his sleeves and started mixing WEST epoxy. He had been warned about strictly adhering to the mix ratios so when using the metered pumps did THREE pumps of resin to ONE pump of the hardener not realizing that the pumps were already doing the math. After three hours and a gallon of resin, he finally laid the last of his carefully tailored bias cut F/G tabbing and was about to congratulate himself. He noticed the glass at the top looking dry so mixed up some more resin and added until he noted a growing pool of still liquid resin at the bottom of the bulkhead. Nothing had even gelled yet and after reading the labels he realized his error.
Poor guy had to pull all the saturated re-inforcements down and was throwing them on a plastic dropcloth and then washing everything down in acetone. He dropped the dropcloth into the bottom of the dink and rowed ashore to go borrow more acetone. He ran down the beach to tell the wife to keep the kids occupied a while longer and went for more acetone. Upon his return was confronted by the angry mothers of the guest kids who were picking up the rascals. Seems that the kids had noted the dink down the beach and all piled in and gotten thouroughly coated in raw epoxy resin and then rolled around in the sand before jumping in the water. The kids all looked like Mexican Wedding Cookies and he was lucky to escape with his life.
After cleaning up the kids, he had to go for more acetone! So be sure you understand the ratios...

[casc27]

Proving yet again that you can't fix stupid. And the ratio for WEST (the regular, old skule stuff) is 5 to 1, not 3 to 1. So, your buddy even got his manual pump mix ration wrong.

Had a buddy who was going to tab in the main bulkhead of his sloop as it was just sitting in a molded channel in the interior molding. You could see it shift when sailing so he bit the bullet and cut the flanges of the channel away and prepped to bond directly to the hull skin. An insane amount of work, especially since he and his wife and daughter were full time live aboards. With plenty of professional advice from the boatbuilders and laminators in the anchorage, he had everything prepped for the big day and the lamination. It was his 6 year old daughters birthday and his wife had a full day of beach party activities for her and about 20 of her friends so he dropped the ladies off at the beach and dinghied back to the boat and rolled up his sleeves and started mixing WEST epoxy. He had been warned about strictly adhering to the mix ratios so when using the metered pumps did THREE pumps of resin to ONE pump of the hardener not realizing that the pumps were already doing the math. After three hours and a gallon of resin, he finally laid the last of his carefully tailored bias cut F/G tabbing and was about to congratulate himself. He noticed the glass at the top looking dry so mixed up some more resin and added until he noted a growing pool of still liquid resin at the bottom of the bulkhead. Nothing had even gelled yet and after reading the labels he realized his error.
Poor guy had to pull all the saturated re-inforcements down and was throwing them on a plastic dropcloth and then washing everything down in acetone. He dropped the dropcloth into the bottom of the dink and rowed ashore to go borrow more acetone. He ran down the beach to tell the wife to keep the kids occupied a while longer and went for more acetone. Upon his return was confronted by the angry mothers of the guest kids who were picking up the rascals. Seems that the kids had noted the dink down the beach and all piled in and gotten thouroughly coated in raw epoxy resin and then rolled around in the sand before jumping in the water. The kids all looked like Mexican Wedding Cookies and he was lucky to escape with his life.
After cleaning up the kids, he had to go for more acetone! So be sure you understand the ratios...

[Soñadora]

Proving yet again that you can't fix stupid. And the ratio for WEST (the regular, old skule stuff) is 5 to 1, not 3 to 1. So, your buddy even got his manual pump mix ration wrong.

Had a buddy who was going to tab in the main bulkhead of his sloop as it was just sitting in a molded channel in the interior molding. You could see it shift when sailing so he bit the bullet and cut the flanges of the channel away and prepped to bond directly to the hull skin. An insane amount of work, especially since he and his wife and daughter were full time live aboards. With plenty of professional advice from the boatbuilders and laminators in the anchorage, he had everything prepped for the big day and the lamination. It was his 6 year old daughters birthday and his wife had a full day of beach party activities for her and about 20 of her friends so he dropped the ladies off at the beach and dinghied back to the boat and rolled up his sleeves and started mixing WEST epoxy. He had been warned about strictly adhering to the mix ratios so when using the metered pumps did THREE pumps of resin to ONE pump of the hardener not realizing that the pumps were already doing the math. After three hours and a gallon of resin, he finally laid the last of his carefully tailored bias cut F/G tabbing and was about to congratulate himself. He noticed the glass at the top looking dry so mixed up some more resin and added until he noted a growing pool of still liquid resin at the bottom of the bulkhead. Nothing had even gelled yet and after reading the labels he realized his error.
Poor guy had to pull all the saturated re-inforcements down and was throwing them on a plastic dropcloth and then washing everything down in acetone. He dropped the dropcloth into the bottom of the dink and rowed ashore to go borrow more acetone. He ran down the beach to tell the wife to keep the kids occupied a while longer and went for more acetone. Upon his return was confronted by the angry mothers of the guest kids who were picking up the rascals. Seems that the kids had noted the dink down the beach and all piled in and gotten thouroughly coated in raw epoxy resin and then rolled around in the sand before jumping in the water. The kids all looked like Mexican Wedding Cookies and he was lucky to escape with his life.
After cleaning up the kids, he had to go for more acetone! So be sure you understand the ratios...

I have to say, I did that once...ONCE! I figured it was wrong when the 5 pumps on the big pump just about filled up the mixing container. Figured at $100/gal I better double check since at that rate I'd be out of resin in 3 sets.

Raps, that story does not sound comfortable. What a drag for those guys, humor for us

[epoxymoron]

I was filing in some deep scratches with west epoxy mixed with cabosil. It's been about 18 hrs, above 7 Celsius and I was hoping to start sanding. But the epoxy doesn't seem to have fully cured. It is still tacky and gummy yet hard. I've never seen this. I use the pumps supplied with new resin and 205 hardener. It did cool off to about 7 over night but when I left the job site yesterday? The epoxy had at least 3 hours around 15 Celsius. Help

The problem is the temperature. Also your description as "tacky and gummy yet hard" contradicts itself. Many people mistake or confuse blush with undercured epoxy - that I understand. But if it's gummy then by definition it's not hard. I always ask when people call with this issue 'can you indent it with your thumbnail? If you can't then what you're feeling on the surface is the blush and it comes of with water. That said, it still may not be cured enough to sand to a dust at that temp. - give it a couple days.

Certainly the pumps are not perfect. If you were using the pumps and the resin and hardener were at the same temperature there's a chance it's ratio related. When working in cold temps it's a good practice to keep the resin and hardener warm. Dispense and mix it indoors if practical for where you're working. If not, a 25 W bulb in a shop lamp placed inside a cooler keeps the materials warm outside at the job site. Of course it will cool as soon as it hits the cold surface, but the pumps work better and the resin and hardener mix better at or near room temp. The 300 pump set is very handy and given to volume of pump sets we sell they work pretty good, but keep in mind they are made to pump catsup and mustard - not a stiff, viscous epoxy resin at 44F. Pumps that would be fail safe at that wide a temperature range would cost way more than anyone would be willing to pay.

Reading through this thread I read a nearly complete list of misconceptions that still linger in the composites world regarding epoxy. Not water proof? Really? All I can say is - nonsense! That comment doesn't even deserve a response. Resin and hardener are not really 'epoxy' until cured? Oxygen Mask, playing those semantic games only confuses the issue and is not helpful. Polyesters and vinylesters cure by a catalyst that promotes the formation of free radicals that cause the crosslink reaction to proceed through the resin. That's why the MEKP can be added at varying percentages (generally 1%- 2%). Think of those big domino displays - one could simply push the head domino and start the chain reaction (1%) and eventually all the dominos will fall. Or, one could push the head domino and also push a few more random dominos within the display and they would all be down much faster (2%). With epoxy the relationship is 1:1 between the resin and hardener molecules - that's why ratio is much more important. We design our resin/hardener systems to have about a +/- 5% leeway in the ratio for a proper cure. SInce the hardener is not a catalyst, adding more beyond the recommended ratio will cause the cure to plasticize or cure soft. Once all the resin sites have reacted the extra hardener has nowhere to go so it floats in the matrix unreacted and the result is a soft epoxy.

Many polyester boats are successfully repaired with polyester, but all things being equal, epoxy makes significantly stronger bonds in a repairs (mechanical/secondary bonds) to a polyester hull than polyester does. VInylesters are often as good as epoxy for repairs, but if you're a DYI guy you will not easily find quality VE resins while epoxy is readily available and easy to use. Most West Marine stores can get it for you, most don't stock it. Plus, while PE is cheaper, VE is about the same cost as epoxy.

Actually, for cosmetic (non-structural) gelcoat repairs the Marine Tex suggestion was a good one.

Finally, gelcoat is applied over epoxy repairs everyday. The key is 1. well mixed on ratio epoxy. 2. fully cured 3. wet sanded to prep the surface for gelcoat (blush or unreacted amines "kill" the free radical formation in the PE gelcoat and the result is a poorly cured interface between the two resin systems. These interfacial problems can cause the gelcoat to peel off in sheets. But like I said - it's done successfully every day.

[Rasputin22]

Casc,

I seem to recall that the guy was using 209 since this was in the Virgin Islands and he was trying to do the whole job at once in a hot boat interior working alone. As he was pretty new to this, the pro's in the harbor had convinced him to use the 209 Extra Slow Hardener which is a 3.56 to 1 ratio. Not sure if he was doing a half pump, but it really didn't matter. At least he didn't have to worry about it kicking off while still on the kids, but I wouldn't want him washing down my daughter with acetone.
He eventually got the job done right and sailed that old flexy flier Huges 38 around the world TWICE! I doubt it would have done it in its original 'floating' bulkhead configuration. Another guy in the same harbor had a Columbia 36 that had the same moulded channel in the interior liner. He was an ex-pro football center and tightened up his bulkhead with an insert of firehose. He used some crowbars to get a gap started up at the sheer between on the windward side while under sail. It pretty much opened up anyway when sailing! He would yell up to his buddy at the helm to sheet hard and bear away and he would stomp and cuss and through brute force jam the length of firehose into the channel all the way down to the sole. Then they would tack and do the same on the new windward side. After everything was in place they went back to the mooring and drank a couple of six packs of cold beer and then 5200'ed the firehose into place quite neatly. Way easier than the job on the Hughes and seemed to work. The guys at the firestation were great about giving the boaties old firehose for chafe gear and all it cast was the 5200 and the beer and was done it a couple of hours. Who said that centers didn't have any brains?

[fastyacht]

"The problem is the temperature. Also your description as "tacky and gummy yet hard" contradicts itself. Many people mistake or confuse blush with undercured epoxy - that I understand. But if it's gummy then by definition it's not hard. I always ask when people call with this issue 'can you indent it with your thumbnail? If you can't then what you're feeling on the surface is the blush and it comes of with water. That said, it still may not be cured enough to sand to a dust at that temp. - give it a couple days."



+1 very good description.



"Certainly the pumps are not perfect. If you were using the pumps and the resin and hardener were at the same temperature there's a chance it's ratio related. When working in cold temps it's a good practice to keep the resin and hardener warm. Dispense and mix it indoors if practical for where you're working. If not, a 25 W bulb in a shop lamp placed inside a cooler keeps the materials warm outside at the job site. Of course it will cool as soon as it hits the cold surface, but the pumps work better and the resin and hardener mix better at or near room temp. The 300 pump set is very handy and given to volume of pump sets we sell they work pretty good, but keep in mind they are made to pump catsup and mustard - not a stiff, viscous epoxy resin at 44F. Pumps that would be fail safe at that wide a temperature range would cost way more than anyone would be willing to pay."


another +1

Reading through this thread I read a nearly complete list of misconceptions that still linger in the composites world regarding epoxy. Not water proof? Really? All I can say is - nonsense! That comment doesn't even deserve a response.

Nobody challenged its "waterproofness" but the standard boatbuilding stuff is not nearly as effective as a water vapor barrier as people believe. There are much better epoxies for that purpose.

Resin and hardener are not really 'epoxy' until cured? Oxygen Mask, playing those semantic games only confuses the issue and is not helpful.

+1 and he was also simply wrong. Epoxy resin is *epoxy*. Cured epoxy, when fully cured with a stoichiometric mix and no vitrification, loses its epoxy "nature" because there aren't any free epoxide reactive sites left open. Of course RTC wet layup homejob epoxy is never perfect, and never fully cures.

<SNIP>With epoxy the relationship is 1:1 between the resin and hardener molecules - that's why ratio is much more important. We design our resin/hardener systems to have about a +/- 5% leeway in the ratio for a proper cure. SInce the hardener is not a catalyst, adding more beyond the recommended ratio will cause the cure to plasticize or cure soft. Once all the resin sites have reacted the extra hardener has nowhere to go so it floats in the matrix unreacted and the result is a soft epoxy.

+1 and also if too little hardener, similar effect with unreacted epoxides

Many polyester boats are successfully repaired with polyester, but all things being equal, epoxy makes significantly stronger bonds in a repairs (mechanical/secondary bonds) to a polyester hull than polyester does. VInylesters are often as good as epoxy for repairs, but if you're a DYI guy you will not easily find quality VE resins while epoxy is readily available and easy to use. Most West Marine stores can get it for you, most don't stock it. Plus, while PE is cheaper, VE is about the same cost as epoxy.

*most* not many professional repairs to polyester are carried out successfully with polyester. Yes, DIY often find it challenging to get the correct materials--but in this day and age there is no excuse for that except depending on what West Marine is selling you rather than doing your homework. Heck, even West Marine sells Evercoat brand, and Fiber Glast Developments brand Vinylester!

Actually, for cosmetic (non-structural) gelcoat repairs the Marine Tex suggestion was a good one.

Finally, gelcoat is applied over epoxy repairs everyday. The key is 1. well mixed on ratio epoxy. 2. fully cured 3. wet sanded to prep the surface for gelcoat (blush or unreacted amines "kill" the free radical formation in the PE gelcoat and the result is a poorly cured interface between the two resin systems. These interfacial problems can cause the gelcoat to peel off in sheets. But like I said - it's done successfully every day.

+1 on the way to get gelcoat to stick to epoxy--and the common result of taking shortcuts. But all of that nonsense is avoided entirely by learning how to repair a boat properly, with styrenated resins, in the first place. A pro isn't going to waste a lot of time with that epoxy trouble where it has no real benefit and only increases the chance of a fubar job.

I also challenge the notion that amateurs can't handle learning how to use styrenated resins properly. Frankly, they are easier to use than epoxies.

And from a health standpoint, between the epichlorohydrin (carcinogen) bisphenol A (estrogen distruptor) and amine (extreme allergen sensitizer) present in many epoxies (with amine in almost every boatbuilding hardener), I think people are better off avoiding them where possible.

[thefuture]

Great debate. Let's neither side take anything personal and keep the facts coming.

[Cavelamb]

There's probably nothing wrong.
You need TIME and HEAT.

I've been building stuff with epoxy for 15+ years. I've used 5 or 6 brands, major and discount stuff.
Even in the heat of summer, I have never had any epoxy cured enough to sand in 18 hours.

What he said...

[eric e]

There's probably nothing wrong.
You need TIME and HEAT.

I've been building stuff with epoxy for 15+ years. I've used 5 or 6 brands, major and discount stuff.
Even in the heat of summer, I have never had any epoxy cured enough to sand in 18 hours.

What he said...

as above

at 7C you need either special epoxy for cold set or heat

set up a lamp and come back tomorrow

[pauloman]

epoxies take at least a week for full cure and that is at room temp. Many epoxies have very very slow cure at temps under 50 degrees (you need something like winter cure basic no blush marine epoxy if you are working in temps near freezing). Adding fillers generally slows down the cure as well.

In your case I wouldn't even check the epoxy for 4-5 days.

[mad]

Why the fuck don't you guys just postcure the stuff?? Jeez

[DRIFTW00D]

For very small epoxy mixes I pump /pour into one these and a flat cut mixing stick.

And a hair drier to add heat to small jobs when its cool.

[atg]

Of course there is no blanket solution to every problem - In cases poly or vinyl is the way to go - in other cases epoxy. I'm a big fan of Methylmethacrylates too- aside from the smell, limited surface prep and a fast bond - what's not to like? Decay of tensile elongation over time is one - but hey nothing is perfect.

If one is engaged in a non structural repair of a poly boat, by all means use poly resin - if it is structural, something with a better interfacial connection (secondary bond) like vinyl or epoxy may be more suitable - and if it is below the waterline, mositure exclusion effectiveness is alwasy a concern.

And far as Gougeon marketing goes - why wouldn't a company that makes epoxy, keep coming up with applications for its product's use while supplying sound scientific data to support thier claims based on ASTM test methods?

I'm not here to start a shit fight or a Jihad over "my glue is better than your glue" - the long and short is , use the right product for the job and be informed of the available options.

Vinylester single skin powerboat hull, looks to have taken a rock on one of the strakes, about a 6" crack along the strake lengthwise, and a bit of delamination above and below. I think it is 7 layers of 36 oz/yd fiberglass. This is below waterline. Not leaking much if at all.

Couple of questions:

1. Epoxy or vinylester for the repair? I'm coming away from this thread thinking it doesn't matter much; there will be new gelcoat over the top though.
2. How on earth does anyone accurately create a 12:1 bevel on the border of the repair? Measure the depth that you grind away at the center, then multiply by 12 and slope it out that far? You guys are nitpicking the 8:1 vs 12:1 and I'm thinking most people couldn't reliably create either one with an angle grinder, particularly on either side of a 90 degree strake upside down under the hull freehand?
3. Does one just take after the delam section with a chisel and carve out all the flaky bits, then bevel it out with the grinder? I've done a bit of this sort of thing, but Moths are more my speed than a Willard 730.

Thanks for any thoughts.
Karl in LA

[mad]

Of course there is no blanket solution to every problem - In cases poly or vinyl is the way to go - in other cases epoxy. I'm a big fan of Methylmethacrylates too- aside from the smell, limited surface prep and a fast bond - what's not to like? Decay of tensile elongation over time is one - but hey nothing is perfect.

If one is engaged in a non structural repair of a poly boat, by all means use poly resin - if it is structural, something with a better interfacial connection (secondary bond) like vinyl or epoxy may be more suitable - and if it is below the waterline, mositure exclusion effectiveness is alwasy a concern.

And far as Gougeon marketing goes - why wouldn't a company that makes epoxy, keep coming up with applications for its product's use while supplying sound scientific data to support thier claims based on ASTM test methods?

I'm not here to start a shit fight or a Jihad over "my glue is better than your glue" - the long and short is , use the right product for the job and be informed of the available options.

Vinylester single skin powerboat hull, looks to have taken a rock on one of the strakes, about a 6" crack along the strake lengthwise, and a bit of delamination above and below. I think it is 7 layers of 36 oz/yd fiberglass. This is below waterline. Not leaking much if at all.

Couple of questions:

1. Epoxy or vinylester for the repair? I'm coming away from this thread thinking it doesn't matter much; there will be new gelcoat over the top though.
2. How on earth does anyone accurately create a 12:1 bevel on the border of the repair? Measure the depth that you grind away at the center, then multiply by 12 and slope it out that far? You guys are nitpicking the 8:1 vs 12:1 and I'm thinking most people couldn't reliably create either one with an angle grinder, particularly on either side of a 90 degree strake upside down under the hull freehand?
3. Does one just take after the delam section with a chisel and carve out all the flaky bits, then bevel it out with the grinder? I've done a bit of this sort of thing, but Moths are more my speed than a Willard 730.

Thanks for any thoughts.
Karl in LA

If you can't figure out how to work out grinding a scarf and don't have the skills to do so with a grinder, I suggest you stay the fuk away from boat repairs.

[atg]

A subtle, but clearly heartfelt reply.

[_Vegas_]

Of course there is no blanket solution to every problem - In cases poly or vinyl is the way to go - in other cases epoxy. I'm a big fan of Methylmethacrylates too- aside from the smell, limited surface prep and a fast bond - what's not to like? Decay of tensile elongation over time is one - but hey nothing is perfect.

If one is engaged in a non structural repair of a poly boat, by all means use poly resin - if it is structural, something with a better interfacial connection (secondary bond) like vinyl or epoxy may be more suitable - and if it is below the waterline, mositure exclusion effectiveness is alwasy a concern.

And far as Gougeon marketing goes - why wouldn't a company that makes epoxy, keep coming up with applications for its product's use while supplying sound scientific data to support thier claims based on ASTM test methods?

I'm not here to start a shit fight or a Jihad over "my glue is better than your glue" - the long and short is , use the right product for the job and be informed of the available options.

Vinylester single skin powerboat hull, looks to have taken a rock on one of the strakes, about a 6" crack along the strake lengthwise, and a bit of delamination above and below. I think it is 7 layers of 36 oz/yd fiberglass. This is below waterline. Not leaking much if at all.

Couple of questions:

1. Epoxy or vinylester for the repair? I'm coming away from this thread thinking it doesn't matter much; there will be new gelcoat over the top though.
2. How on earth does anyone accurately create a 12:1 bevel on the border of the repair? Measure the depth that you grind away at the center, then multiply by 12 and slope it out that far? You guys are nitpicking the 8:1 vs 12:1 and I'm thinking most people couldn't reliably create either one with an angle grinder, particularly on either side of a 90 degree strake upside down under the hull freehand?
3. Does one just take after the delam section with a chisel and carve out all the flaky bits, then bevel it out with the grinder? I've done a bit of this sort of thing, but Moths are more my speed than a Willard 730.

Thanks for any thoughts.
Karl in LA

First of all you will need to determine the extent of damage - and this can be beyond what is visible to the eye. Interlaminate damage can propagate much farther than the damage you see. Some guys use a dead hammer and "sound" it out - other methods include using a IR camera , but the long and short is you'll want to cut out the damaged material and plan your repair - 8:1 - 12:1 , depending on where the damage has occured (structurally) and what you will be reairing with will contribute to your bevel ratio - more bevel also mean more surface area for your repair to tie to. Grinding the bevel does not have to be dead nuts - closer the better, but don't go out and buy a laser micrometer just yet. If your laminate is 1" thick and you are going for a 12:1, trace the hole in your laminte and draw a 12" line around the repair surface - next grab that trusty angle grinder, some goggles and a full tyvek suit and respirator. and start grinding - by this time you should have your laminate schedule well defined. repair glass that is used sometimes has a stiched chop strand mat in combination with multi-axial woven glass - using this helps with interfacial connection to your substrate and subsequent other layers of glass. After you get this far - then we can discuss laying up the glass, glue and how to form a backing for your repair.

[dreaded]

so, for another question, I'm laying down epoxy onto boards, how do you deal with the edges?

it seems that the epoxy likes to recede from the edge or that gravity takes over a pulls the epoxy over the edge into a drip..

[_Vegas_]

so, for another question, I'm laying down epoxy onto boards, how do you deal with the edges?

it seems that the epoxy likes to recede from the edge or that gravity takes over a pulls the epoxy over the edge into a drip..

if you are using glass, then use peel ply - If you are coating, roll and tip and go wet on wet when you hit the gel stage to build up film thickness

[fastyacht]

Of course there is no blanket solution to every problem - In cases poly or vinyl is the way to go - in other cases epoxy. I'm a big fan of Methylmethacrylates too- aside from the smell, limited surface prep and a fast bond - what's not to like? Decay of tensile elongation over time is one - but hey nothing is perfect.

If one is engaged in a non structural repair of a poly boat, by all means use poly resin - if it is structural, something with a better interfacial connection (secondary bond) like vinyl or epoxy may be more suitable - and if it is below the waterline, mositure exclusion effectiveness is alwasy a concern.

And far as Gougeon marketing goes - why wouldn't a company that makes epoxy, keep coming up with applications for its product's use while supplying sound scientific data to support thier claims based on ASTM test methods?

I'm not here to start a shit fight or a Jihad over "my glue is better than your glue" - the long and short is , use the right product for the job and be informed of the available options.

Vinylester single skin powerboat hull, looks to have taken a rock on one of the strakes, about a 6" crack along the strake lengthwise, and a bit of delamination above and below. I think it is 7 layers of 36 oz/yd fiberglass. This is below waterline. Not leaking much if at all.

Couple of questions:

1. Epoxy or vinylester for the repair? I'm coming away from this thread thinking it doesn't matter much; there will be new gelcoat over the top though.
2. How on earth does anyone accurately create a 12:1 bevel on the border of the repair? Measure the depth that you grind away at the center, then multiply by 12 and slope it out that far? You guys are nitpicking the 8:1 vs 12:1 and I'm thinking most people couldn't reliably create either one with an angle grinder, particularly on either side of a 90 degree strake upside down under the hull freehand?
3. Does one just take after the delam section with a chisel and carve out all the flaky bits, then bevel it out with the grinder? I've done a bit of this sort of thing, but Moths are more my speed than a Willard 730.

Thanks for any thoughts.
Karl in LA

8:1 is *never* enough bevel and 12:1 is only good enough if you are adding additional backing. A proper scarf needs to develop the whole fiberglass strength across the bondiine in shear.

[dreaded]

so, for another question, I'm laying down epoxy onto boards, how do you deal with the edges?

it seems that the epoxy likes to recede from the edge or that gravity takes over a pulls the epoxy over the edge into a drip..

if you are using glass, then use peel ply - If you are coating, roll and tip and go wet on wet when you hit the gel stage to build up film thickness

I'll give that a try and a +1 to whomever made the scale recommendation..

[DRIFTW00D]

One thing is If u can get at it 12/1 the inside of the patch area also. Gets the patch stuck on both sides of the hull.

[bruno]

I have been having some issues lately with peelply on wetpreg, unbagged, as it goes B stage wrinkling, mostly on mat. I suspect that it is just not good with mat but it also could be the material is different and is stretchier? Of course the PP goes on smooth and is squeegeed flat so this is a change from how it is left. One time I am sure there was too much moisture in the (wooden) substrate as there were air bubbles trappedin, this is room cure Proset and West, ambient about 85 F+\-. With the mat it seems like resin bubbles migrating to the surface, spaced about 1/2" 1 cm. When I am doing my own work I usually make the last layer cloth and then PP, if mat then no PP.

[_Vegas_]

Of course there is no blanket solution to every problem - In cases poly or vinyl is the way to go - in other cases epoxy. I'm a big fan of Methylmethacrylates too- aside from the smell, limited surface prep and a fast bond - what's not to like? Decay of tensile elongation over time is one - but hey nothing is perfect.

If one is engaged in a non structural repair of a poly boat, by all means use poly resin - if it is structural, something with a better interfacial connection (secondary bond) like vinyl or epoxy may be more suitable - and if it is below the waterline, mositure exclusion effectiveness is alwasy a concern.

And far as Gougeon marketing goes - why wouldn't a company that makes epoxy, keep coming up with applications for its product's use while supplying sound scientific data to support thier claims based on ASTM test methods?

I'm not here to start a shit fight or a Jihad over "my glue is better than your glue" - the long and short is , use the right product for the job and be informed of the available options.

Vinylester single skin powerboat hull, looks to have taken a rock on one of the strakes, about a 6" crack along the strake lengthwise, and a bit of delamination above and below. I think it is 7 layers of 36 oz/yd fiberglass. This is below waterline. Not leaking much if at all.

Couple of questions:

1. Epoxy or vinylester for the repair? I'm coming away from this thread thinking it doesn't matter much; there will be new gelcoat over the top though.
2. How on earth does anyone accurately create a 12:1 bevel on the border of the repair? Measure the depth that you grind away at the center, then multiply by 12 and slope it out that far? You guys are nitpicking the 8:1 vs 12:1 and I'm thinking most people couldn't reliably create either one with an angle grinder, particularly on either side of a 90 degree strake upside down under the hull freehand?
3. Does one just take after the delam section with a chisel and carve out all the flaky bits, then bevel it out with the grinder? I've done a bit of this sort of thing, but Moths are more my speed than a Willard 730.

Thanks for any thoughts.
Karl in LA

8:1 is *never* enough bevel and 12:1 is only good enough if you are adding additional backing. A proper scarf needs to develop the whole fiberglass strength across the bondiine in shear.

As the saying goes "Never say never" - I would contend that a non structural solid laminate repair can be effectivly performed at 8:1 (or less ) . Let's say you had a storage locker or live well that got speared with something creating a 2" hole in 1/2" laminate (that was beefy to begin with) - grinding a 4" bevel to repair that non-structural panel would be more than suffcient - would it hurt going out to 6"? No, unless you were impeded by a surface detail that you really don;t want to mess with... But I do agree that anything structural , 12:1 minimum - and choose your materials, and laminate schedule carefully - and pay close attention to surface prep - I'd say 60% of repair failures occur becuase of improper surface prep -

[fastyacht]

Haha well of course for non-structural you don't need 12:1. Heck, a lot of repairs are "non-structural" and acceptably so. 10mm hole punched in the foredeck of your sailing dinghy? A little guts fills the hole...and it is ok because you know that the whole deck isn't needed for structural integrity. For instance if you have to repair the mast step of a laser, you drill a big-ass hole in the deck, do the repair, and then install an inspection port...just don't put it in the wrong place! :-)

Bottom of your boat, watertight envelope, of say collision damage to the topsides, different story of course.

[fastyacht]

I have been having some issues lately with peelply on wetpreg, unbagged, as it goes B stage wrinkling, mostly on mat. I suspect that it is just not good with mat but it also could be the material is different and is stretchier? Of course the PP goes on smooth and is squeegeed flat so this is a change from how it is left. One time I am sure there was too much moisture in the (wooden) substrate as there were air bubbles trappedin, this is room cure Proset and West, ambient about 85 F+\-. With the mat it seems like resin bubbles migrating to the surface, spaced about 1/2" 1 cm. When I am doing my own work I usually make the last layer cloth and then PP, if mat then no PP.

Are you using chopped strand mat with epoxy? That is typically a no-no because the type of sizing on the mat is only compatible with styrene.

[_Vegas_]

I have been having some issues lately with peelply on wetpreg, unbagged, as it goes B stage wrinkling, mostly on mat. I suspect that it is just not good with mat but it also could be the material is different and is stretchier? Of course the PP goes on smooth and is squeegeed flat so this is a change from how it is left. One time I am sure there was too much moisture in the (wooden) substrate as there were air bubbles trappedin, this is room cure Proset and West, ambient about 85 F+\-. With the mat it seems like resin bubbles migrating to the surface, spaced about 1/2" 1 cm. When I am doing my own work I usually make the last layer cloth and then PP, if mat then no PP.

Hmmmmm ...are you wetting out CSM (shop strand mat) with epoxy? Have you verified that the CSM is epoxy compatible? A lot of CSM uses a binder that disolves in styrenated resins, but not in epoxy. This would inhibit a thorough wet out of the fibers and when cured would create "dry" spots that would look like air bubbles.

Also if you work the fabric too much, you can work higher viscosity resins into a froth and as they cure and exotherm - the viscosity goes down just before gel stage (in thicker films or stacks), this would release some entrapped air allow it come to the surface. If you have a resin system with a good open time, you can put the resin on your glass and then wait while it saturates prior to working it in. I especially liek this when working with carbon - in fact, depending on the part or project - I'll wet the substrate, lay the carbon over it and allow the resin to uptake on base surface, and then go over the face surface with the remainder of the resin to wet out the part properly. Of course over or under wetting the fabric is undesireable - with a hand layup I calculate about a 50% resin to fiber ratio - vac bag around 40-45% and infusion around 35-40%. with infusion though you have to account for transfer tubing and a bit left in the feed pot. Having a feed pot go dry and pulling a slug of air into your part sucks.

[bruno]

I have been having some issues lately with peelply on wetpreg, unbagged, as it goes B stage wrinkling, mostly on mat. I suspect that it is just not good with mat but it also could be the material is different and is stretchier? Of course the PP goes on smooth and is squeegeed flat so this is a change from how it is left. One time I am sure there was too much moisture in the (wooden) substrate as there were air bubbles trappedin, this is room cure Proset and West, ambient about 85 F+\-. With the mat it seems like resin bubbles migrating to the surface, spaced about 1/2" 1 cm. When I am doing my own work I usually make the last layer cloth and then PP, if mat then no PP.

Are you using chopped strand mat with epoxy? That is typically a no-no because the type of sizing on the mat is only compatible with styrene.

Agreed, and I am a bore on the topic of using epoxy soluble mat but I am not in charge of every lam I work on. As noted also, I do not see the point of using peel ply and any mat, even in a bag, do not like it.

[bruno]

I have been having some issues lately with peelply on wetpreg, unbagged, as it goes B stage wrinkling, mostly on mat. I suspect that it is just not good with mat but it also could be the material is different and is stretchier? Of course the PP goes on smooth and is squeegeed flat so this is a change from how it is left. One time I am sure there was too much moisture in the (wooden) substrate as there were air bubbles trappedin, this is room cure Proset and West, ambient about 85 F+\-. With the mat it seems like resin bubbles migrating to the surface, spaced about 1/2" 1 cm. When I am doing my own work I usually make the last layer cloth and then PP, if mat then no PP.

Hmmmmm ...are you wetting out CSM (shop strand mat) with epoxy? Have you verified that the CSM is epoxy compatible? A lot of CSM uses a binder that disolves in styrenated resins, but not in epoxy. This would inhibit a thorough wet out of the fibers and when cured would create "dry" spots that would look like air bubbles.

Also if you work the fabric too much, you can work higher viscosity resins into a froth and as they cure and exotherm - the viscosity goes down just before gel stage (in thicker films or stacks), this would release some entrapped air allow it come to the surface. If you have a resin system with a good open time, you can put the resin on your glass and then wait while it saturates prior to working it in. I especially liek this when working with carbon - in fact, depending on the part or project - I'll wet the substrate, lay the carbon over it and allow the resin to uptake on base surface, and then go over the face surface with the remainder of the resin to wet out the part properly. Of course over or under wetting the fabric is undesireable - with a hand layup I calculate about a 50% resin to fiber ratio - vac bag around 40-45% and infusion around 35-40%. with infusion though you have to account for transfer tubing and a bit left in the feed pot. Having a feed pot go dry and pulling a slug of air into your part sucks.

Good points, thanks, I like to pull resin up through the lam also. No, these seem like resin pockets rather than air, we might have frothed the resin a bit, crew used cheap roller sleeves, another nono, but we were moving fast and airrolling lightly. It almost looks to me like the resin comes up to the surface non-uniformly resulting in rich pockets that bumpnthe cloth. Basically, I do not myself use PP with mat and suspect this is the cause- too much resin coming out of the mat. Thanks.

[BobBill]

Mixing filled resin systems is a little tricky but obvious doable with epoxy - the problem inherent is the viscosity differentials. If you have a thick resin and a thin hardener you end up mixing your brains out to achieve a homogenous solution - and the chances of off ratio parts of the thickened mixture is increased. Now if your hardener and resin were both already thickened with your filler then you have a better chance of homogeneity, but if you go that far, might as well mix the resin and hardener and then add your filler (less process steps to success).

+1. And that goes for all Vegas wrote after that.

[_Vegas_]

Ahhh yes - the old "floating" fabric debacle. Sure too much resin will cause your fiber to "float" in the glue and lose connection with your substrate potentially adversely affecting your laminates performance. +1 on not using peel ply in contact with CSM - however I have had good luck with hybrid fabircs like 1708 that combine a bi-axial and CSM that is stiched on using peel ply on the Bi-ax face. Hell I even cheated and poured glue on to the peel ply over dry spots in the laminate and drove glue in to the stack through the release fabric - works just fine. I don't think I'd attempt to infuse a CSM stack, too many opportunites to get a resin lock condition. Throwing CSM with a gun is groovy for fast production - Wetting it out by hand isn't much fun - especially if your polyester is kicking on ya mid layup.

[SpinnakerTed]

It's on the cold side here. This spot light has help. I could use two more.


Restoration of a C15. http://plasticclassi...=4744&start=150

[SpinnakerTed]

It was 11.5 deg C all night, but the epoxy stays much warmer under the blanket and just a 75 watt lamp.

Restoration of a C15. http://plasticclassi...=4744&start=150

[SpinnakerTed]

This is how she spent the night. The lamp is tucked up under the cockpit, the blanket hold in the heat.

Restoration of a C15. http://plasticclassi...=4744&start=150

[TornadoCAN99]

Sorry if slightly off topic but there seems to be a large knowledge bank here I'd like to tap.
I'll be starting a bike frame build shortly...bamboo sections with carbon tow wrapped at joints ("lugs" in bike-speak). The build kit uses West System 205 I believe. Any pros/cons of switching that to the slower kicking flavour? Thought I'd like to maximize my work time as I'm new at the layup patterns.

Also, earlier on, someone mentioned not to apply excess heat to help cure the epoxy...I've used a little heat in previous repairs to no apparent fault. Just a low temp blow from hair dryer or small space heater against a large panel covered in a box outside overnight.

Thanks.

[_Vegas_]

IF you need extra working time and your shop temps are 60F or above, there is nothing wrong with going that route with the 206, if you are in the tropics and have shop temps of 80+, definitely go the slow. or go the extra slow of 209 -

Or get all three and mix up hybrid cure time mixtures ....

Also you can use a little heat to help the cure along, but you don't want to ramp too fast. start at 80 and increase 10F / hour til cure should be ok - max out at 150 or 160 F

[fastyacht]

remember the outgassing problem.

[_Vegas_]

remember the outgassing problem.

What outgassing prblem? If it goes off too fast, any entrapped moisture can boil off if it get's too hot. Other than that, high solids epoxy contains very little solvents that can outgas.

[F18 VB]

remember the outgassing problem.

What outgassing prblem? If it goes off too fast, any entrapped moisture can boil off if it get's too hot. Other than that, high solids epoxy contains very little solvents that can outgas.

What about the wood outgassing when heated to 150 F?

[_Vegas_]

Ahhhh ha there is that - the air in channles of wood will do that. Yes when applying the first coat of anything over wood its better to have the wood at a higher temperture than the shop to avoid that. If applying multiple coats you can drive the through cure with extra heat after the first coat has set up..

[F18 VB]

So, if you want to cure the epoxy over wood at 150 F, you need to heat the wood up higher than that first? Does that mean that the wood should be heated up, allowed to cool to near room temp, apply the epoxy, and then slowly ramp the temperature up to 150 F?

Or, are you saying that the first coat should be cured at room temp and then subsequent coats can be cured at 150? Does that mean that wood outgassing beneath cured epoxy is not a problem?

[JumpingJax]

Since you'll be using 3D shapes, it's also a good idea to remember that as the mix is heated, the viscosity is reduced (before gel, that is). If you heat too high too fast, you'll be at risk of runs and drips. Best to let the heating wait until the mix gels and the exotherm has peaked. Then you can heat to accelerate cure as Vegas suggests.

On horizontal surface coatings and very thin vertical coatings, immediately after wetting out, a heat gun (or the Admiral's hair dryer) can help surface leveling, but go very lightly or you can make ripples that are awful looking and a bitch to sand out. You can guess How I Know These Facts.

[_Vegas_]

Since you'll be using 3D shapes, it's also a good idea to remember that as the mix is heated, the viscosity is reduced (before gel, that is). If you heat too high too fast, you'll be at risk of runs and drips. Best to let the heating wait until the mix gels and the exotherm has peaked. Then you can heat to accelerate cure as Vegas suggests.

On horizontal surface coatings and very thin vertical coatings, immediately after wetting out, a heat gun (or the Admiral's hair dryer) can help surface leveling, but go very lightly or you can make ripples that are awful looking and a bitch to sand out. You can guess How I Know These Facts.

+1

The additional heat applied, even to a room temp cured epoxy, will drive a post cure and increase the the properties.

[Oxygen Mask]

So, if you want to cure the epoxy over wood at 150 F, you need to heat the wood up higher than that first? Does that mean that the wood should be heated up, allowed to cool to near room temp, apply the epoxy, and then slowly ramp the temperature up to 150 F?

Or, are you saying that the first coat should be cured at room temp and then subsequent coats can be cured at 150? Does that mean that wood outgassing beneath cured epoxy is not a problem?

You want to heat the wood to a bit more than ambient temp, then coat, so it's cooling as you are working and as it cures. Otherwise tiny bubbles can form in your epoxy from outgassing of entrapped air in the wood if the temp is climbing while you're working (or even possibly from the exotherm of the epoxy.)
Once that first coat has set you can add more coats and heat them higher, the air trapped in the wood is there to stay.
I've always let it fully cure, but I wonder if 'green' is enough? At any rate, you don't need to ramp up the heat to get a better cure until later, you can do it any time - even next summer.

I used to set my part, or boat, out in the sun for a while, then move it into the shade or shop and apply my epoxy. (Doesn't work so well in winter...)
In winter, I'd heat the shop overnight to say 70F, then turn the heat down to 60 and go to work.

A related trick, if you are having trouble with some bubbles forming, wave a heat gun/hair dryer over the area and they magically disappear. I've had this help too if I discover a bubble in my wetout after the resin has begun to cure, the heat lowers the viscosity and lets me work that bubble out. Sometimes..