Gelcoat - what am I doing wrong?

[Sail4beer]

Like JSB said

wipe the area with some methyl ethyl keytone peroxide and it should cure. There should be no reason to remove it if it is still tacky. Go over it with more gelcoat; the wax hasn’t risen out of the gelcoat. In cooler weather you can thin the gelcoat with about 10% acetone or xylene to help the gelcoat get through the preval and put in a little more mekp than usual-about 3% by volume. And that will help it stay warm and cure fast.

 

[jgbrown]

Like JSB said

wipe the area with some methyl ethyl keytone peroxide and it should cure. There should be no reason to remove it if it is still tacky. Go over it with more gelcoat; the wax hasn’t risen out of the gelcoat. In cooler weather you can thin the gelcoat with about 10% acetone or xylene to help the gelcoat get through the preval and put in a little more mekp than usual-about 3% by volume. And that will help it stay warm and cure fast.

It depends on how long it's been, I tried this once and then it cured to a nice hard finish on the surface.  It chipped off easily though, didn't cure all the way through.  Wipe it off, start over is better IMO.  If it's within a few hours, then I'd fog it with hair spray and warm it up a little with a heat gun(I put one finger next to the repair, if your finger is uncomfortable, so is the gelcoat...).  Keep warming it and letting it cool every 5 minutes for about 20 and then leave it be.  Should cure rock hard. 

Thinner preference for me: thin with styrene first(should end up feeling about like coffee cream when you drip it off a stir stick) then thin a little more with acetone.  I find the acetone flashes off on the way out the spray tip, nice for getting good spray pattern, but doesn't let it flow on the surface easily, the styrene hangs around longer and does a better job of that.  Waxed gelcoat in thin layers has rarely worked well for me, easier to apply neat then fog with cheap hair spray over top(5 minutes or more after application not right away) or mylar as above and no problems, even the surface layer dries hard and sandable.  I've tried thinning with xylene(and mek once for giggles).  Styrene+ a touch of acetone always worked the most consistently for me.  MEK thinned gel behaved strangely in the cup after, xylene as well. 

 

[Navig8tor]

Cover the area with waxed baking paper leave a day, buy your own roll don't borrow from the missus, just trust me on that.......

If you are filling chips or voids fill with gel then put the waxed  baking paper over the spot and then drag a razor blade over it - not too many times 1-3 max this will help fill and fair before the stuff kicks off.

 

[Gouvernail]

It really doesn’t matter. Gelcoat with wax I nit will weather differently than your boat and in a few months your repairs will look like a damned fool screwed up the boat.

as long as you are starting over anyway, use straight gelcoat and either out ova over it or add an extra cost of gelcoat to be washed off.

here is a nice idiot proof set of directions:  

http://schrothfiberglass.com/GelcoatRepairPrimer.htm

 

[hobot]

You don't use aerosil or Colloidal silica make gelcoat into a paste?

 

[Slowboat]

I have learned the hard way, of doing gelcoat over epoxy, all of the amine blush must absolutely be removed for the gelcoat to harden.

warm water and plenty of soap is the best way to do this.

 

[Autonomous]

Suggestions to occlude air from unwaxed gelcoat are requested.

I'm repairing some chips on compound surfaces and mylar film was a disaster. I don't want to buy a quart of waxed gelcoat or wax additive for these few < one teaspoon chips
The repairs needed more gelcoat so I sprayed the heck out them with Aqua Net hairspray after round two. I don't know if it will be satisfactory. Waxed paper seems it would still suck. How about Johnson paste wax if the hair spray does not work? Dissolve some paraffin or Johnson wax in acetone?
I am open to abuse and suggestions.

Thanks.

 

[See Level]

PVA, prevail sprayer or even Windex type spray bottle work.

 

[phill_nz]

i never used waxed gelcoat for repairs
just normal gelcoat .. no air anything .. no pva just gelcoat ( if i was in a hurry i might add a touch of cobalt and sometimes dma as well )
when you do it fill it proud by 2-3mm and it will go off
when it has reached the rubbery stage slice off most of the excess with a razor blade ( using a carving motion ) .. this will save a lot of sanding and keep the surrounding area from getting to thin .. i then use 400 - 600 wet n dry with warm soapy water to get it to the almost finished stage while it is still soft ( do it lightly or it will dig bits out ) .. finish it with 800 - 1000 and brasso when its hard

i have used this approach as a cosmetic finish on items and also on molds where any scratches or flat spots are a real problem

it works
its fast
its easy

 

[blurocketsmate]

^^^ I've been doing it like this since I was 10, racing Sabots. I used plastic wrap, or pieces of sandwich bags.

 

[Autonomous]

The suggestions are appreciated. I just can't see driving 30 miles round trip or waiting five days for something to be delivered. I'll wash the hair spray off tomorrow and see what's up.

This is my first gelcoat job. I got lucky with the color match and did blend enough for two tries. The boat is less than a year old, lives in the shop and the patches will be out of sight so there's that.

Keep the hints and abuse coming!

 

[Autonomous]

The hair spray hack works!
I'm sure the proper methods are better though.

 

[DrewR]

Way back when I used to add a small amount of Johnson liquid wax to gelcoat and it worked fine. I'm not sure it's even available still but it did seal the gelcoat for a perfect finish.