Gel Coat

[joe]

Greeting,

Does anyone know anything about Gel Coat?

I'm amazed how difficult it's been to find the products locally and find information on how it works.

I'm considering it to coat HDU, and EPS Foam.

Here's what I think I know? It's much like automotive enamel except it can be built up very thick, dry's fast, and is hard.

Thanks for the help.

[tmerrill]

Joe,

This looks like a pretty good start point:

http://www.evercoat.com/imgs/pis/GELCOAT.pdf

Tim

[bryson]

Joe, What is the question on gel coat? In a previous life I had a fiberglass fabrication business.
Bryson

[navigator7]

Hi Joe,
Gel coat is hard, brittle and not very strong until backed up by something like fiberglas.
I used to get baked spraying the stuff into half molds of gillnet boats back in the 70's.
Chopper guns were fun to use.

Sunlight is not its friend.

I've had some experience making faux rock. During this training I learned fiberglas and gel coating products are outlawed in many areas. Often requiring licensing to use the product legally. Facilities that satisfy a governmental agency are required and if any complaints are received your biz is road kill.
Where I live, price limits its use.

I guess the long and short of it is .... I learned to use as far cheaper product to accomplish the same results as fiberglass. Which was portland, moose milk, and lots of fiber.

I suppose you are thinking about fiberglas signs or some such but maybe this is a good time to bring up vacuum forming?

A former business partner of mine owned a vacuum forming company. They built all kinds of stuff but especially those push Mocha dispensers common at many gas stations. ABS plastic was the product of choice.

The used their own 3 axis CNC mill to make a built up mold from wood and used the same mill to mill off the flashing.
The mold had tiny holes drilled through it and bottom of the mold was not unlike a plenum.

ABS plastic is very strong and comes in sheets. The only remaining problem is an oven big enough to cover a mold.

Speaking of ovens.........Hope we all have time to be thankful for all the great things about our country even during the swirling manure storms.

[joe]

Thanks Tim, that answered a bunch of questions.

Bryson, here's what I'm thinking. It appears this material would be excellent for coating out HDU which is a real pain. Also wouldn't it be good to use as a build up and surface hardner for EPS?

I'm a real believer of High Build Primer because it fills pin holes, and sands smooth. Wouldn't Gel Coat be a better choice with the color mixed in. Right now I have to order the Centari mixed for me and it's expensive. Does this material need a primer?

Is it tricky to apply lots of coat with out sagging? I see the mixing colors comes in snll tubes. Wouldn't it be fairly easy to get the deliclate colors I often use? The cost of gallon of Centari is about $140 while Gelcoat is much less.

I have too many questions, on this topic, to post here but appreciate any advice.

[Gary Campbell]

Joe...
If I were going to coat foam I would use vinylester resin instead of gel coat. Reasons (for and against):

VE is not as brittle and has a strength sililar to epoxy
Will not work on EPS as the styrene content(any fiberglass product) will melt EPS, OK on HDU
Use a dump gun with replacable liners to spray
Gel coat, due to the added pigments, is many times more expensive and you dont need color.
Can be "mixed" to set in minutes
Make sure you add sanding wax
Make sure you have pressurized air breathing system. When spraying styrene diluted products without one, you can hear brain cells popping like the 4th of July.

There are epoxy fomulations that allow a fast set. I think they can be sprayed if thinned with Zylene. They will work on both foams without the "melt". They are more impact resistant than the glass product, but cost more too. Also require a dump gun.

Any other questions, give me a call.
Gary

[tparr]

Joe: With your level of interest and depth of questions, it would be best if you contacted the tech reps from several of the suppliers companies. These people are a world of information and will be very helpful.

[bryson]

Joe, You could apply 30 to 40 mils at a time if you don't thin it which I wouldn't. I have attached a picture of the spay gun that I made for this purpose. I removed the vent tube and replaced it with a small regulator. I just increase the pressure until it spays evenly. Probably around a 1/2lb. One thing about gel coat or in Garys reply, it's not an enamel so it doesn't air dry. The surface will stay tacky. You can wipe that off with acetone or you can spray a light coat of PVA on the gel coat as soon as you are done with the build up. You can add wax to the mix as Gary mentions but then you have to deal with removing the wax for painting. I prefer the PVA, it's quick and easy and rinses off with water. Also, you do not need to prime gel coat.
Bryson
pressure gun
\Officepc\my documents\Projects\pressure gun.pdf (25.3 k)

[joe]

Gary,

I'll have to check out Vinylester Resin.

I got this idea from my next door neighbors who make experimental, high tec, model airplanes for weather research. There spraying gel coat over eps foam. Are we talking about the same product? Their gel comes from Fiberglass.com and doesn't look very expensive.

BW,

Thanks for the photo. Is the added small pressure line a conversion to a pressure pot?

[bryson]

Joe, The small line is connected to a small regulator that enables you to pressurize the cup so that you can spray unthinned gel coat. I just T'd off the quick connect.
Bryson