Boating How-To’s - School Me on Gel Coat

OK, so I have some minor glass repairs to make on my Stratos, and I got color-matched gel coat from Midwest Mobile Supply. Perfect match... but it's not "waxed". I plan to brush it on and then sand smooth - I won't be spraying. I'm clueless about MEPK as well.

So, I surfed around here and on YouTube for application techniques. I saw the mylar/plastic covering method, and the method where you spray PVA over it with a throwaway sprayer. What I'm really looking for is info on what I can add to my gel coat to let it cure uncovered. The areas I'm coating are odd-shaped and the plastic covering method would be tricky, if not impossible without exposing air.

A friend told me he had a wax additive added to his, and it cures in open air. Can one of you gurus explain that to me? I'm good with glassing and epoxy, but gel coating is new to me.

Thanks in advance

Gel coat is made to be sprayed into a mold where the "exterior" surface is air inhibited (by the mold surface) and to cure tacky on the "interior" surface so that laminates can be applied without sanding or surface prep. So when we use it backwards, like in repair work, we have to inhibit air from the surface during cure. You can do this by adding a very small amount of wax additive or by spraying PVA on the surface a few minutes after spraying the gel coat. Or you can add Duratech, which makes the gel coat spray better and adds longevity and gloss retention, and dries tack free.
Wax additives will lighten the color slightly. Styrene is the normal thinner @ up to 20%. Any more than 20% and you'll shorten its longevity.

So... for my brush application, can I use Duratech?

What "wax additive"...? Can you be more specific, or maybe include a product name?

This is great info, I appreciate the help and want to learn.

fiberglass inc iam very intrested in learning how to compound and buff would you be willing to explain to me if payed you a fee thanks

Wax additive is simply styrene with parafin mixed into it. It is available anywhere they sell composite stuff. I think West Marine stocks it or can order it. Yes, you can brush gel coat w/Duratech but don't expect too much in the way of finish.
Bluewater - I'm probably not the best source for polishing information. I've only been at this game 45 years and i'm still learning. Look for GlennE's thread, good information there.

OK, so I have some minor glass repairs to make on my Stratos, and I got color-matched gel coat from Midwest Mobile Supply. Perfect match... but it's not "waxed". I plan to brush it on and then sand smooth - I won't be spraying. I'm clueless about MEPK as well.

So, I surfed around here and on YouTube for application techniques. I saw the mylar/plastic covering method, and the method where you spray PVA over it with a throwaway sprayer. What I'm really looking for is info on what I can add to my gel coat to let it cure uncovered. The areas I'm coating are odd-shaped and the plastic covering method would be tricky, if not impossible without exposing air.

A friend told me he had a wax additive added to his, and it cures in open air. Can one of you gurus explain that to me? I'm good with glassing and epoxy, but gel coating is new to me.

Thanks in advance

PVA is OK but a little durance clear additive is the best. wax is third. Almost never does the wax paper method seal and lay flat on any boat surface. I would at least by a prevail. I used to use them all the time professionally when it was little job with no compressor available. The prevails are cheap for the work it will save you over brushing. At least use a throw away foam brush and don't use it to long. It will go away on its own.

Here is a write up I did on my gel coat project. I tried to put it all in one place after having gone on the same gel coat educational oddessy. Man-up and buy a decent compressor. I bought it for the gel coat, but now use it for all knds of stuff. You won't regret buying it.

http://www.westcoasthighliners.com/my-shiney-hiney/

SBD,

I'm a contractor, so I have compressors, but I don't have a gun. Guess I should just man-up and buy a gun and give it a try.

If you already have a compressor there is no reason to not go for it, and its your perfect opportunity to get revenge on home cheapo.

This gun works great for gelcoat... http://www.homedepot.com/h_d1/N-5yc1v/R-100668715/h_d2/ProductDisplay?catalogId=10053&langId=-1&keyword=spray+gun&storeId=10051

When they ask you if you want the warranty say YES.
When is becomes plugged with gelcoat go get a new one.
Repeat as needed.

SBD,

Nice write-up on that other site... thanks for the info. Looks like exactly what I needed.

My brother is going to let me use one of his guns and I'll give it a shot. I just have to buy some SB-112 to act as a tie coat between my LBI epoxy and the gel coat.

Thanks to all for the info... much appreciated. Wish me luck.

My brother is going to let me use one of his guns and I'll give it a shot.

I'd buy the $45 gun from THD before ruining my brothers! ;cool;

I did all of the plumbing and heating in his house... he owes me anyway.

;)

Gel dries quick so you have to have a plan for spraying....I did my whole bottom and cleaned the gun when it started too kick inside...also if it does plug the spray end with your fingers and hit the air it will put back pressure into the cup and blow out the drying gel turd...my painter showed me that trick....I mixed enough for the whole job and only kicked what i could spray through one quart, cleaning as needed and i sprayed the hull on my 256 Dusky...Duratec is a must IMO

are you all speaking of the duratec clear attitive? and at what ratio?

How do you tell if your gelcoat is "waxed" or is not "waxed" in order to apply properly? I have some factory gelcoat that triton sent me that I believe is not waxed but not really sure? Also I have some small dings on the side of the hull (white) and would like to fill those in. How do you work with gelcoat on a vertical surface like the hull sides?

If you're repairing small dings you can thicken the gelcoat a bit with collidial silica and tape a small piece of wax paper or plastic wrap over the repair while it cures. Just be sure it's in full contact with the new gelcoat. That way it will cure either way. After if cures, wet sand it so it's level and polish it out.

If you're repairing small dings you can thicken the gelcoat a bit with collidial silica and tape a small piece of wax paper or plastic wrap over the repair while it cures. Just be sure it's in full contact with the new gelcoat. That way it will cure either way. After if cures, wet sand it so it's level and polish it out.

Thank you for the tips!

For small dings or repair areas, definately use the Preval. It works great for this. I used it for small areas with Duratec mixed in and with the Duratec, you do not need to add wax. It will air cure.
Also, I don't like to cover with paper or other materials as it will smear/spread the gelcoat and makes the sanding harder to blend in.
Mask off the area a little larger than you want, sand it and work the area of damage properly, wipe down with Acetone and then spray the area and allow some of the blending to go out gradually towards the masking area, but not fully to the tape lines so you don't build up a layer that you would have to sand down. Then once cured, you can sand the orange peel and overspray with 320/400/600/800 and then polish it to a high gloss.

For large areas, use the spraygun with Durtec. I like Epic just sprayed the bottom of my 25' Grady, sanded the orange peel and polished up. It is very nice and slick!
Like Epic, between each quart of spray, use Acetone to clear gun while mixing the next quart with some help then go back into it until done.

By far, Duratec is top notch and makes it much easier.