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Conquistador_del_mar
04-04-2011, 12:37 PM
What does gelcoat have in it other than being a pigmented polyester resin? I am thinking it might have a wax agent. I have also always heard that it has UV inhibitors - what is that chemical? Just yesterday, I mixed up a batch of custom colored maroon polyester resin paste to do a few repairs on a Martini that I recently bought using a pigment kit from Evercoat. I catalyzed it and filled a few scratches and gouges after cleaning them with lacquer thinner and covered them with wax paper to let them harden. I went back out last night and wet sanded and buffed out a few of them. They look virtually perfect, but I don't know if I can expect a discoloration in the future. That is why I am asking about what special chemicals are in gelcoat. Thanks in advance, Bill

gcarter
04-04-2011, 02:32 PM
Bill, it may have more to do w/the mfgr of the gel than anything else.
It won't have wax unless you requested it or it is so stated on the can.

gcarter
04-04-2011, 02:34 PM
Something else I learned to do on the TR was to use 2" wide celophane strapping tape instead of wax paper.....it really holds itself in place.

mike o
04-04-2011, 03:43 PM
Bill, Depends if its an ISO or an Ortho gelcoat. Iso is more $ and stronger. They are called extenders and thixotropes in non chemical jargon...:wink:. I have UV inhabitors added to my stuff, but I dont know what they are called, but cost more.:yes: This PFD will get Ya started.:yes: Sit down in your favorite chair and mix a drink, on a rain-e day....:kingme: http://www.acmanet.org/research/spi_papers_90_thru_99/SPI_papers_90/1990-08.pdf Oh ya, these chemicals prices are going thru the roof......Again and never come down.

Conquistador_del_mar
04-06-2011, 12:13 AM
Something else I learned to do on the TR was to use 2" wide celophane strapping tape instead of wax paper.....it really holds itself in place.


Bill, Depends if its an ISO or an Ortho gelcoat. Iso is more $ and stronger. They are called extenders and thixotropes in non chemical jargon...:wink:. I have UV inhabitors added to my stuff, but I dont know what they are called, but cost more.:yes: This PFD will get Ya started.:yes: Sit down in your favorite chair and mix a drink, on a rain-e day....:kingme: http://www.acmanet.org/research/spi_papers_90_thru_99/SPI_papers_90/1990-08.pdf Oh ya, these chemicals prices are going thru the roof......Again and never come down.

Thanks for the replies. I am guessing that since my boats rarely are exposed to UV rays, I probably won't see any color changes. I remember how badly some of the Sea Ray's gelcoat faded quite a few years ago - some in less than a year. I probably Imroned at least 15 of them in the 80s and early 90s. I might try the celophane trick - I have used wax paper and taped over it with tape for many years. That trick would do it all in one shot. Bill

mike o
04-06-2011, 08:05 AM
There's some double chemical bonds in the red pigment molecules that are more susceptible to UV from the sun :yes:, that makes the red fade faster. The thick packaging tape lays down flat (no crinkles) so less sanding...:kingme: Right Mr.C.........:crossfing:

gcarter
04-06-2011, 08:21 AM
I might try the celophane trick - I have used wax paper and taped over it with tape for many years. That trick would do it all in one shot. Bill

And it isolates the gel from air, if necessary.

Walt. H.
04-06-2011, 11:16 AM
celophane works best keeping the gel nice and flat for less wet sanding and additional reapplication to fill in voids caused by wax paper, but wax paper should be used when the area has curves or lips such as the engine hatch recess lip.
But for large areas you'll have to spray on PVA, which does a better job anyway, and can be sprayed on by using a hand trigger squeeze spray bottle that produces a mist like the glass cleaner found under your kitchen sink storage cabinette. :wink:

justleft
04-07-2011, 05:42 PM
Thanks !! Great info. I have alot of chips and dings to fill.

"There's some double chemical bonds in the red pigment molecules that are more susceptible to UV from the sun :yes:, that makes the red fade faster."

Don't give me that happy face Mike.
I'm in the middle of wet sanding my red side '86 22c. Oh it's the dance with the devil.... 1000 grit will take 5 yrs, 600 seems just right.
Now if I play really nice I won't burn thru....

mike o
04-07-2011, 06:02 PM
Protectant 303 helps with fading. When wet sanding, pay attention to the color of the particles mixing with the sanding water. White-ish particles is the top surface oxidized gel. When you start seeing the original gelcoat color in the water, its time to go to a less aggressive paper. :wink:

gcarter
04-07-2011, 06:27 PM
Don't give me that happy face Mike.
I'm in the middle of wet sanding my red side '86 22c. Oh it's the dance with the devil.... 1000 grit will take 5 yrs, 600 seems just right.
Now if I play really nice I won't burn thru....

Well, I did my whole hull, deck, and cockpit to 2500 paper in several months.
You can do it!

mrfixxall
04-07-2011, 07:26 PM
have any of you tried mixing duratec clear and gel 1:1 ?
i have found that you dont need wax,cellophane,wax paper of even pva for it to cure,,the nice part about it is it sprays nice and flat with minimal orange peel and buffs out like clear coat to a brilliant shine..

Walt. H.
04-08-2011, 01:15 AM
have any of you tried mixing duratec clear and gel 1:1 ?
i have found that you dont need wax,cellophane,wax paper of even pva for it to cure,,the nice part about it is it sprays nice and flat with minimal orange peel and buffs out like clear coat to a brilliant shine..

No but I know of a fellow who has done quite a few late 50's and early 1960's tail fin Glastrons and other vintage fiberglass boat restorations where he has to remove all the old crazed and cracked gel-kote off right down to the cloth material, and the Duratec is the stuff he swears by when he applies his final coat.

And I always thought it was strange and impossible to mix the two together, a clear paint product into gel-kote. Just because you would think the two would be like mixing paint thinner into water base latex paint, the results are it Curdles like spoiled milk but not the Duratic & gelkote. And like you said he said also, lays out smoother with less wet sanding to achieve a factory hi-gloss finish!

gcarter
04-08-2011, 04:19 AM
I must say, this is a fascinating subject concerning the Duratec clear.
I did a little searching and found that US Composits carries it at a pretty good price. Also, they claim it's not a paint but a polyester product.
Additionally, this is what they say about the process;

Duratec Clear Hi-Gloss ADDITIVE
"Duratec Clear is a special blend of polyester polymers that produce excellent clarity, color and light stability, chemical resistance and a non-wax, tack free high gloss finish when added to a gelcoat at a 1:1 ratio for repairs and to upgrade tooling gelcoats".