Working with Gelcoat

I applied 2" glass keel strips on the bow and stern of my pintail this week, and that part went really well. I sanded those a bit, and applied color-matched unwaxed gelcoat that GRO had sent me. I quickly discovered that using plastic wrap as an air-barrier would ruin the smooth finish of the gelcoat, so I hastily switched to spraying on mold-release to cover the remaining 3/4 of the gelcoated areas. I was using a the top of a spray bottle because it’s what I had on hand, but it couldn’t spray the thick mold release in a fine mist, so I ended up using a lot more of the stuff just to get good coverage.

I need to redo the small section that I messed up with the plastic, and I’d like to find a better way to apply the mold release. Can anyone recommend a sprayer that works better for this stuff? It has sort of an oily consistency. Maybe one of those olive oil sprayers would work? Or the pump-up sprayers used for spraying small amounts of finish or paint? I believe I’ve seen that kind of thing in woodworking catalogs but I’ve never used them for anything.

Any recommendations?

Thanks, Nate

Gel re-application
For spot repairs, which is what you’re doing, we brush catalyzed, un-waxed gel on, let it set with mild lamp heat, wipe with acetone and sand to 2000 grit before using buffing out with rubbing compound.

I had thought that unwaxed gelcoat wouldn’t cure if it wasn’t covered somehow. Are you saying that I can just leave it be, and it’ll cure? That would certainly simplify things.

You could always get one of those
Prevail (sp? ) sprayers @ Home Depot. 10.00 or something like that.

You can spray gelocat with it, clean it and then spray PVA.

Side not here is you have to thin the gelcoat a little to much with this dinky thing IMO but it works.

If you time it right, you couls simply brush on your pva too … Its o.k. to use a lot of it. Washes right off.

I’ll look for that prevail sprayer. Also I wasn’t sure if I could wait for the gelcoat to set some before covering it. That’s good to know.

so, why not waxed gel coat?
I usually go for the waxed version.

If the gel coat does not have it, you can always add a bit of waxed styrene.

Are there any differences in the finished job?

No need to cover. It cures fine as is without cling wrap of mold release spray over.

My experience
As onno said you can let the gel coat set up a bit and then apply with brush.

It will be set up enough that no brush strokes will show. No need to buy a sprayer.

I tend to use gel coat that is not waxed so I can add more layers if I want to and not have to sand between.

sackly, if you bugger up wax, yo gotta
go back and ‘start over’ of sorts by 1. Waiting, 2. Sanding, 3. Hoping … you got it all prepped right for secondary bonding. Wax also changes the color ever so slightly.

Pro repair guys … you can also mix in about 25 - 50 % Clear Duratec and spray as normal WITHOUT wax or mold release over it …

Only the surface won’t cure
While it’s definitely messy, wiping off the uncured top layer will reveal cured gelcoat beneath. Personally, I prefer to use finish (waxed) gelcoat and tint it myself. For keep strips, most people just use black or white, so color matching isn’t necessary. Besides, once the color has faded, matching it is nearly impossible.

using what I’ve got
I’m using unwaxed gelcoat because that’s what the kind folks at GRO stuck in my last order free of charge. My boat is British Racing Green hull/deck, with yellow trim, so while I don’t care a ton about looks, black or white would be a bit strange for a keel strip on my boat.

The yellow keel strip looks great, and the stuff I sprayed with PVA came out looking real nice.

Waxed styrene is a good idea. I had forgotten that’s an option. Maybe for the final repair I’ll get some of that, or use a better sprayer for the PVA.

I use

– Last Updated: Apr-17-09 11:35 AM EST –

a Badger # 250 air brush and plug it into my compressor set at around 40 psi to spray PVA

inexpensive and works fine

Best Wishes

some on sale low as $6.00