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Preval Sprayer and Flex-Mold

Posted By: srm

Preval Sprayer and Flex-Mold - 08/30/16 04:10 PM

Anyone ever used a Preval Sprayer for spraying gelcoat? My one friend said they don't work very well, but he's a professional fiberglass repairman so he's used to using high end equipment. I just have a few small areas of deck that I'm putting back together and can't really justify buying a compressor and spraying equipment. So my other options are to try to brush on gelcoat or see if my buddy can spray it for me.

Same question regarding Gibco Flex-Mold for repairing non-skid - anyone have experience with this? It's kind of pricey at $54 for a 1' x 1' square but looks like it could be the best option for matching the original non-skid texture on the deck.

sm
Posted By: rehmbo

Re: Preval Sprayer and Flex-Mold - 08/30/16 04:46 PM

With regard to the Preval sprayers, one of my good friends (John Bauldry) uses them almost exclusively and had showed me how to do it. They work amazingly well for small jobs. Have to thin the gel with acetone to get it to spray smoothly. The acetone vaporizes before the gel hits the boat so it doesn't impact application very much.

As to the quality of the result - I did a decent size 4"x6" repair on the side of my boat last summer and I challenge anyone to find it.
Posted By: srm

Re: Preval Sprayer and Flex-Mold - 08/30/16 06:23 PM

Good info, thanks!

How much life do you typically get from one canister? I have four areas to spray - two about 8" x 10" and two about 5" x 8".

sm
Posted By: rehmbo

Re: Preval Sprayer and Flex-Mold - 08/30/16 06:33 PM

It lasted a lot longer than I expected - I generally ran out of gel in the jar long before it began to affect spray-ability. I guess it depends on temperature and how much hardner you mix in.

I think you could theoretically clean them out for reuse. But at $5 each, its hardly worth the labor.

Each coat had to cure overnight before sanding. In my case 3 coats = 3 preval sprayers.
Posted By: rehmbo

Re: Preval Sprayer and Flex-Mold - 08/30/16 06:38 PM

I also did the daggers and rudders on our club's Tiger a couple years ago. One jar full was more than enough for a solid coat on one side of each. I did 2 coats on each side, so in the end it was 4 Preval sprayers.

Proper surface prep and sanding is always key. Spraying gel is the easy part. smile
Posted By: catman

Re: Preval Sprayer and Flex-Mold - 08/30/16 09:01 PM

Actually I would use medium Lacquer thinner instead of acetone. Thin it just enough to get it to spray.

As far as the nonskid goes, I waxed a area of the good non skid and laid some lightweight glass on it and make my own pattern. Did it on a hobie 18 with fairly good results. Not perfect but good.
Posted By: srm

Re: Preval Sprayer and Flex-Mold - 08/30/16 10:05 PM

Not a bad idea regarding the non-skid. Considering I have 2 TheMightyHobie18's, I could just splash a mold off the good boat and use it to mold the gelcoat on the one I'm fixing.

sm
Posted By: Jake

Re: Preval Sprayer and Flex-Mold - 08/31/16 01:37 PM

Originally Posted by srm
Not a bad idea regarding the non-skid. Considering I have 2 TheMightyHobie18's, I could just splash a mold off the good boat and use it to mold the gelcoat on the one I'm fixing.

sm


You can also use 100% silicon caulk to make a non-skid pattern mold with...it has the added benefit of being flexible so you can apply that pattern to other areas of the boat that aren't necessarily the same shape as the area you made the mold from. You'll need some sort of mold release to get the silicon to remove cleanly...can't recall what the right stuff is at the moment, though. I'm sure the internet can help.


Edit...welp, here you go: http://www.martha.net/2014/05/making-a-100-silicone-caulk-mold/
Posted By: srm

Re: Preval Sprayer and Flex-Mold - 09/17/16 01:50 AM

Any recommendations on getting the preval to spray better? Today was my first attempt. I thinned the gelcoat with styrene at about 10% and got a lot of spatter. I added a bit more and it improved somewhat but still got a fair amount of spatter and it seemed to be having a tough time sucking in the gelcoat. Thin it more? I believe the recommendation I read was to thin between 10-20%. Should I go more? I'm also wondering if the surfacing wax I added played a roll in how well it sprayed.

sm
Posted By: waterbug_wpb

Re: Preval Sprayer and Flex-Mold - 09/17/16 09:56 PM

not sure since I never used wax in the gelcoat mix, but that could possibly be it..

I've sprayed thinned gelcoat with the Prevail for smaller jobs with good results.

Thinned it to just a little thicker than car-paint consistency and sprayed several layers to build thickness (letting it flash off between coats), and then spraying that green stuff that smelled like chloraseptic to seal the top coat (mold release)

Course, I'm in the tropics (high heat/humidity) so flashing off took about a minute..
Posted By: srm

Re: Preval Sprayer and Flex-Mold - 09/18/16 01:59 AM

Thanks for the reply, but not having ever worked with car paint, that description isn't all that helpful for me. Approximately what percentage are you using gelcoat to styrene? 50/50, 75/25, 90/10?

sm
Posted By: catman

Re: Preval Sprayer and Flex-Mold - 09/18/16 03:36 PM

Two things. Use medium lacquer thinner not styrene. Do not use the wax. The wax clogs the sprayer. Spray the area with PVA right after the last coat or Hair spray. I have gel-coated many boats and have tried many methods.
Posted By: srm

Re: Preval Sprayer and Flex-Mold - 09/18/16 09:03 PM

Are you also using the Preval to spray the PVA?

sm
Posted By: catman

Re: Preval Sprayer and Flex-Mold - 09/19/16 12:12 PM

Yes.
Posted By: waterbug_wpb

Re: Preval Sprayer and Flex-Mold - 09/19/16 02:35 PM

Originally Posted by srm
Are you also using the Preval to spray the PVA?

sm


use it in a separate prevail sprayer

And car paint is usually thinner than house paint. Does that help?

Think maybe hot pancake syrup?? Flows relatively quickly, but leaves a residue in the jar.
Posted By: waterbug_wpb

Re: Preval Sprayer and Flex-Mold - 09/19/16 02:37 PM

Originally Posted by srm
Thanks for the reply, but not having ever worked with car paint, that description isn't all that helpful for me. Approximately what percentage are you using gelcoat to styrene? 50/50, 75/25, 90/10?

sm


I can't be sure of the exact ratio, since the gelcoat/additives/pigment(s) I was using may be different than yours. I went for the viscosity rather than an exact ratio.
Posted By: srm

Re: Preval Sprayer and Flex-Mold - 09/20/16 04:30 PM

OK. Thanks, I've been messing around with it. I used the preval to spray the PVA and it worked relatively well, so I won't put wax in the gelcoat anymore. Still trying to figure out exactly how much to thin the gelcoat, but I'll figure it out.

One thing I noticed, the preval really doesn't seem to have a lot of pressure when spraying. However when I was cleaning it out afterward, I flipped it over (like you would do when cleaning a can of spray paint) and the thing blasted out a nice powerful plume. Would be nice if it had that kind of power when spraying upright.

sm
Posted By: catman

Re: Preval Sprayer and Flex-Mold - 09/20/16 10:10 PM

It takes a bit of fooling around. You can thin it more. Just takes more coats to achieve coverage.
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