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What am I doing wrong? Two layers of west 207 on bare okoume plywood and basswood. Applied with a west style yellow foam roller. Second layer went on when the first layer was still tacky but wouldn't peel when pressed with a gloved finger. The finish comes out very rough and takes a lot of sanding to smooth out. Any ideas? 

Sorry for the flipped pics.. 

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those could be little bubbles. If so, a pass with a hair dryer will increase viscosity for a moment and let them pop. On the plywood, it might have raised the grain a bit.

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I had the same experience putting new bulkheads in our SC 27.  The second coat of epoxy went on a lot smoother, and then the varnish on top was smoother yet. 

If you want it to be perfect by all means sand between coats, but I personally think you don't have to.  I didn't, but I had the advantage that I could lay the bulkheads flat while putting the coatings on, which helped things to flatten out. 

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32 minutes ago, Zonker said:

Maybe the first coat had some outgassing, causing little bubbles. The 2nd coat magnified the bubbles?

It is so similar to how mine looked I think it is an artifact of putting epoxy on meranti.  Meranti has a very deep grain, and also sucks a lot of the epoxy into the grain on the first coat.  Hence the rough texture.  

I switched to Epiglass varnish after the second coat of epoxy and the bulkheads turned out fine, once there was enough coating there to flatten out.

OTOH the pine or whatever the trim is does look bubbled.  That usually happens when the material heats up during the cure.  It is important to make sure the material is cooling or staying at the same temperature during the cure.  

See: https://www.westsystem.com/instruction-2/epoxy-basics/problem-solver-faq/#bubbles

You can also get bubbles with too-aggressive mixing of the epoxy, introducing air bubbles into the mixture.  These then appear on the coated material but are easily brushed out.

That's the limit of my knowledge on this.  Good luck.

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2 hours ago, Raz'r said:

those could be little bubbles. If so, a pass with a hair dryer will DEcrease viscosity for a moment and let them pop. On the plywood, it might have raised the grain a bit.

FTFY

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11 hours ago, MichalD said:

What am I doing wrong? Two layers of west 207 on bare okoume plywood and basswood. Applied with a west style yellow foam roller. Second layer went on when the first layer was still tacky but wouldn't peel when pressed with a gloved finger. The finish comes out very rough and takes a lot of sanding to smooth out. Any ideas? 

Sorry for the flipped pics.. 

IMG_20201108_120740.jpg

IMG_20201108_120717.jpg

IMG_20201108_115605.jpg

Not clear what you are doing 

always remember that wood breaths 

 

in when cooling ...out when heating 

to avoid bubbles , outgassing ... warm up your surface , turn off the heat source.... then epoxy during the cooling cycle 

in real world conditions avoid applying any coating over  cold bare wood in the morning ...Waite until afternoon

Plywood always soaks epoxy and leaves a grainy surface when painting vertical surfaces 

When vertical ,  you have no choice but sand smooth and apply multiple coats   

If  possible use the flow coat technique on horizontal surface 

the finish ,after a single flow coat,  is very good 

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11 hours ago, Rain Man said:

You can also get bubbles with too-aggressive mixing of the epoxy, introducing air bubbles into the mixture.  These then appear on the coated material but are easily brushed out.

You don't even have to be aggressive.  Even moderate mixing can introduce bubbles.  It's surprising how much air epoxy can hold.

 

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Yes, bubbles are an issue. However much of the first epoxy coat lumpyness can be attributed the a fuzzy surface on the wood. Sanding causes microscopic fibers on the surface which combined with epoxy's unfriendly behavior of being sticky thick and runny all at the same time makes for a bit of pain. Especially with softwoods like you have chosen. Varnish has less of this issue while also sanding much easier.

Also epoxy gets a bit warm in cure causing air in the wood to expand into bubbles. Some people heat the wood before painting so it cools during cure, shrinking the air.

Use the epoxy very quickly so that it flows most easily.

Learn to love sanding.

When epoxy is painted on a smooth surface other than wood, or the second coat after sanding, it can be very smooth.

 

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Use a squeedgee on the first coat, roll it on give it 15 minutes or so, then squeedgee left to right, give in a few minutes, then squeedgee top to bottom.  Might serve to pay attention to the direction of the grain on the last pull... grin.  Evercoat body filler size squeedgees have a bit of an angle to the corners, west systems spreaders are almost too wide to get an even pressure pull, you can score them with a box cutter, and take 2-3 inches off one side. 

If you have any excess on the squeedgee as you go, drag it across the top of a the mixing bucket and take it off the piece, and wipe the squeedgee on a rag. If you have any excess in the corners take a lint free painters rag and mop it up.  If your resin starts to go to snot consistency, squeedgee up whatever will come off the sruface and put it back in the mixing pot. 

If the film thickness, is thin enough the surface tension isn't high enough to hold or blow a bubble, which means that coat fills what it will fill, and on verticals all that will hang in the voids is hanging.  If you rolled on a full build coat, the places that blow a bubble on the next coat would be a crater in the finish, if you'd started there.  

After 45 minutes to an hour, once your mixing pot has gone green, brush/roll on a coat.  If you have bubbles still, squeedgee it again.  Some species of plywood drink more than others, and you can't really roll on a build coat until they've had their fill, without getting stuck in a sanding cycle of hell.  Once you sand the top off a bubble, you have pin holes in the surface from the bubbles that you cut the top off of with the sandpaper, you are coating the entire piece to try to fill pin holes.

Don't do that, epoxy isn't paint, and does not flow out like high build primer.  So only put it where you need it, until you can get a good even film coat without re-creating surface defects. 

My lucky number is 3 coats rolled after the last bubble.  Takes an afternoon of waiting once an hour, but if you roll on three full build coats after the last bubble, following the chemical bond window, then normally you've got enough film thickness that almost all the shiny spots left after DA sanding with a fine paper disappear, and you sand it once.

Then from there on out if you've got low shiny spots you can tape around them and use an acid brush to detail them up, as they should be few enough in number that it doesn't make sense to recoat the whole piece, and re-sand the whole piece.

Squeedgee works great with primer too.  An awlgrip rep showed it to me, as you can break the surface tension over the pin holes that a rolled or brushed coat spans.  Brushes do better than rollers for getting into defects.  If you have compressed air, you can cut a 2 inch chip brush bristle down to an inch or so long and have one stiff enough to mush into grain lines and pin holes... but the bristles need to be blown out, outside the shop or you have a lot of hair to sand out...  

 

 

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Zach - thanks for describing the spreader method - it makes sense.  When you say primer I am assuming awlgrip 545 which is a bitch to roll and tip (thankfully it sands easy).  I might give the spreader method a try.

On a side note I have had good luck using a misting spray bottle and DNA for removing bubbles in the final horizontal epoxy layer.  Just a fine mist above the surface and the bubbles flow out and disappear.  For me it seemed to work better than the torch method.  

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Thanks for the suggestions! I'll try some of these techniques out.

I tried to be mindful of the temperature not increasing. I did not wipe the plywood down with a lint cloth after sanding (when I tried that before it lifted a lot of half attached grain up). It seemed to get worse after the second coat. 

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On 11/13/2020 at 5:16 PM, MichalD said:

Thanks for the suggestions! I'll try some of these techniques out.

I tried to be mindful of the temperature not increasing. I did not wipe the plywood down with a lint cloth after sanding (when I tried that before it lifted a lot of half attached grain up). It seemed to get worse after the second coat. 

That was my experience too.  Meranti has to be treated a little differently.  Until the surface splinters are embedded in epoxy, they can be pulled up.  I decided to just keep adding layers until I had a surface that was sandable.  

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On 11/14/2020 at 2:38 AM, yoyo said:

Zach - thanks for describing the spreader method - it makes sense.  When you say primer I am assuming awlgrip 545 which is a bitch to roll and tip (thankfully it sands easy).  I might give the spreader method a try.

On a side note I have had good luck using a misting spray bottle and DNA for removing bubbles in the final horizontal epoxy layer.  Just a fine mist above the surface and the bubbles flow out and disappear.  For me it seemed to work better than the torch method.  

The best solvent for epoxy is isopropyl alcohol(rubbing). You will be surprised how much better it is than denatured (ethyanol + methanol). In non-Covid times you can get a liter of 91% for $3 at CVS. 

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12 hours ago, CaptainAhab said:

The best solvent for epoxy is isopropyl alcohol(rubbing). You will be surprised how much better it is than denatured (ethyanol + methanol). In non-Covid times you can get a liter of 91% for $3 at CVS. 

That 9% of impurities might hurt the resin. I was told by more than one person to use denatured at no more than 10%. But you can buy penetrating or low viscosity Epoxy. 

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