Gelcoat, with or without wax

[Scherfz1]

Fiberglass Coatings sells Vapor brand guns, granted much more than you can get them from Amazon or Northern tool.

i used that green one from northern tool by vapor, worked very well.

 

[Woodonglass]

Doing Gelcoat in a Mold and On an exterior hull are Totally different animals. If you're going to shoot the entire hull you should totally grind off ALL the old Gelcoat and get her down to fresh Glass. You Don't use wax in the gelcoat until the final coat. You'll need 4-6 coats. Dump guns are the best for spraying Gelcoat. Temps, Humidity etc all play a vital role in external spraying of Gelcoat. It's significantly more difficult than spraying it in a mold. That's why the majority of boat restorations opt to paint their hulls instead of Re-Gelcoating them. Not saying you can't but if you're not set up properly to do it then your success ratio goes way down.

I totally respect your years of experience and welcome your knowledge here on the Forum. As I stated previously Spraying Gelcoat on an existing hull and spraying it in a Mold are two completely different processes. There is a chemical process in the curing of Polyester Based products but...Gelcoat and ALL polyester resin products are Air-Inhibited cured. ALL of them. Again in a Mold situation the Gelcoat is applied to the mold that is treated with a release agent. After the Gelcoat has been sprayed in The fibeglass resin is sprayed over it. This SEALS the Gelcoat from the air and thus allows it to fully cure quickly. ALL polyester resin will cure to a Non Tacky surface eventually but temps and humidity can make this a Long process and getting it fully cured as quickly as possible is the desired method, especially with GelCoat. Even though it will eventually cure with time, It won't be as Hard and durable as it would if Air is not allowed to get to it while the chemical process is occuring. When it's sealed from the air it occurs very quickly. In a mold once the glass has been shot over the Gel the resin doesn't need to cure quickly and remain tacky for an extended period. Additives do help with the flow of the product and thin it which aids in the spraying. . Thinning with styrene is the recommend method but it's some nasty stuff . Thinning is a necessary evil but it should be the minimum to allow for application. All I'm doing is passing on what I learned from two of this Forums Resident Experts. OOOPS and Ondarvr. Ondarvr has been in the Resin Business for over 40 Years and Testifies in Court cases for ALL the NorthAmerican Resin Manufacturers. He's forgotten more about this stuff than I'll ever know but during his time on this forum he taught me and the rest of the members a LOT about the right and wrong methods. The reason for removing the old gel is that it will absorb contaminants over the years and this can cause blistering and cracking of the new Gel. It's NOT absolutely necessary to do this but a really good sanding of the overall hull IS if you want to ensure good results. Everyone is free to do as they see fit, Me and the others here on the forum only try to give answers based on our experience and knowledge. Everyone has to make their own decisions on what to follow. I stated in my previous answer that Wax if used, ONLY goes in the final coat. PVA is sprayed on about 20 minutes after the last coat of Gel is applied and then washed off in about an hour. For small repairs you can tape plastic over the area and get the same results as Wax or PVA.

I'm just an Dumb Old Okie trying to pass on my knowledge from Experience and "Lernin'" that I've gained from the Forum Members. Use it as you see fit.

Here's a thread from 11 years ago where Ondarvr talks about Gelcoating. I sure wish he was a part of this Forum.

https://www.boatdesign.net/threads/gel-coat-cure.22713/

https://www.boatdesign.net/threads/gel-coat-reactions.36424/

 

[Zippys Gelcoat and Fiberglass Repair]

Nope I definitely respect what others are doing. Looks the they are doin it fine. I just may put theft shoe on before the right on I'd ya catch my drift. I've only used PVA when we were gonna pop.Mold. always remove old gelcoat via router tip for cracks. Orbital DA for whatever else. I wipe my paint spots off with acetone really good before sanding. 400 800 1000 sand and buff. I listen to what others say.

we're the boys from Illinois we come from
caves and ditches.
Hoosier by Birth
illinoisan by force

 

[BillP]

I totally respect your years of experience and welcome your knowledge here on the Forum. As I stated previously Spraying Gelcoat on an existing hull and spraying it in a Mold are two completely different processes. There is a chemical process in the curing of Polyester Based products but...Gelcoat and ALL polyester resin products are Air-Inhibited cured. ALL of them. Again in a Mold situation the Gelcoat is applied to the mold that is treated with a release agent. After the Gelcoat has been sprayed in The fibeglass resin is sprayed over it. This SEALS the Gelcoat from the air and thus allows it to fully cure quickly. ALL polyester resin will cure to a Non Tacky surface eventually but temps and humidity can make this a Long process and getting it fully cured as quickly as possible is the desired method, especially with GelCoat. Even though it will eventually cure with time, It won't be as Hard and durable as it would if Air is not allowed to get to it while the chemical process is occuring. When it's sealed from the air it occurs very quickly. In a mold once the glass has been shot over the Gel the resin doesn't need to cure quickly and remain tacky for an extended period. Additives do help with the flow of the product and thin it which aids in the spraying. . Thinning with styrene is the recommend method but it's some nasty stuff . Thinning is a necessary evil but it should be the minimum to allow for application. All I'm doing is passing on what I learned from two of this Forums Resident Experts. OOOPS and Ondarvr. Ondarvr has been in the Resin Business for over 40 Years and Testifies in Court cases for ALL the NorthAmerican Resin Manufacturers. He's forgotten more about this stuff than I'll ever know but during his time on this forum he taught me and the rest of the members a LOT about the right and wrong methods. The reason for removing the old gel is that it will absorb contaminants over the years and this can cause blistering and cracking of the new Gel. It's NOT absolutely necessary to do this but a really good sanding of the overall hull IS if you want to ensure good results. Everyone is free to do as they see fit, Me and the others here on the forum only try to give answers based on our experience and knowledge. Everyone has to make their own decisions on what to follow. I stated in my previous answer that Wax if used, ONLY goes in the final coat. PVA is sprayed on about 20 minutes after the last coat of Gel is applied and then washed off in about an hour. For small repairs you can tape plastic over the area and get the same results as Wax or PVA.

I'm just an Dumb Old Okie trying to pass on my knowledge from Experience and "Lernin'" that I've gained from the Forum Members. Use it as you see fit.

Here's a thread from 11 years ago where Ondarvr talks about Gelcoating. I sure wish he was a part of this Forum.

https://www.boatdesign.net/threads/gel-coat-cure.22713/

https://www.boatdesign.net/threads/g...actions.36424/

You may want to consider learning from different sources. Funny how that works. Ondarvar is the one who continually told me stryene isn't for thinning poly and acetone was the correct material...to the point of personal attacks. Which was totally bogus info and anyone experienced in the industry knows it. The funny part is yrs later he changed his tune to say styrene is resin thinner. It always was and still is. This isn't the only subject we butted heads on. It's easy to search way back on this forum and see the flip flops.

 

[Zippys Gelcoat and Fiberglass Repair]

You don't want to use wax (or PVA - my favorite) till the last coat, because as your previously waxed coat begins to set, the wax migrates to the surface - so spraying on top of wax won't properly stick to the previous layer.

I use 2 cheap (Harbor Freight) sprayers for larger areas, 1 for the gel, the other for the PVA - which gets sprayed-on as a final coat. I wait a few days (I know, overkill), and wash-off the PVA with warm water. Works like a charm.

Ya see, the thing is I just feel most people put WAY to much thought in the repair. Wax 3rd coat, wax paper to cure an so forth. It started with someone telling me i had to use wax in my gelcoat. I was like what? I was so confused i called my old gelcoater. He said most all gelcoats have wax on it. What we used at the plant did. So I was like...proceed as normal. He agreed. I'm definately not trying to be a smart butt. BUT i was a HIGHLY sought after gelcoat specialist. I personally could do a 180 hull from Starboard to Port including aft, with paint spots, sand buff flaws then glaze in approximately 25 mins. A Mariah 212 I could do in about 35. They continually blew the liners of dome Godfrey boats out with too much air which resulted in multi fractures and spider cracks along the inner radius for the entire starboard, port and aft. They were doing one a week. I personally did them in one DaY. That's because I knew how to do production. I do know quite a lot

 

[Jeff Fro]

Looking to order some gel coat to finish a repair to a jet ski that a neighbor's grand kids jacked up. So, what I am reading is no was in the gel-coat as long as I cover up the repaired area with wax paper? Then wipe with acetone, 220,400, and then 600 grit sanding?

Thanks.