Old school gel?

[John Hanafin]

Hello,
I am a Brit living in Nigeria, I have started a project of repairing some old fiberglass boats and also turning a wooden banana boat into a sleek gel coated boat for beach trips. Problem im having here is materials, I can get matt, cloth, resin, catalyst , accelerator etc . But the only gel I can get is clear, the supplier (shady character) tells me he can provide any colour pigment I require and the mix will make my gel coat finish good as if pre mixed. Is this legit? I heard somewhere that this is how it was done before.

[TeddyDiver]

Old school GelCoat= resin, colour paste and parafin

[John Hanafin]

Parafin? What kind of ratio would that be?

Cheers.

[tunnels]

Originally Posted by John Hanafin

Hello,
I am a Brit living in Nigeria, I have started a project of repairing some old fiberglass boats and also turning a wooden banana boat into a sleek gel coated boat for beach trips. Problem im having here is materials, I can get matt, cloth, resin, catalyst , accelerator etc . But the only gel I can get is clear, the supplier (shady character) tells me he can provide any colour pigment I require and the mix will make my gel coat finish good as if pre mixed. Is this legit? I heard somewhere that this is how it was done before.

Hell yes it all starts its life as clear!! , just order the coloredpigment you need and a pail of clear and add x amount of pigment and stir like hell and there you have it !! Rather than a whole pail of the one color just mix what you need an save the clear for other jobs of differant colors . Paraffin wax !not unless you are making flo coat !!

[TeddyDiver]

Originally Posted by tunnels

Paraffin wax !

Parafin oil.. smth like 1 to 3 % but don't recall well. In Nigeria if there isn't anything with a knowledge of the manufacturer and product info it's propably "home brewed" you can aswell mix it yourself..

[tunnels]

Originally Posted by TeddyDiver

Parafin oil.. smth like 1 to 3 % but don't recall well. In Nigeria if there isn't anything with a knowledge of the manufacturer and product info it's propably "home brewed" you can aswell mix it yourself..

Candle wax!!!!

[TeddyDiver]

I'm glad you get amused of so little
To get the mixture tixotropic add some silica (like cap-o-sil)

Originally Posted by tunnels

Candle wax!!!!

Bees wax is as good tunnels.................................


John,

forget about that gelcoat nonsense! In both cases you mention, it is not the right material.

When you sheath a wooden boat, you have to use epoxy, not polyester, to start with.
Poly does not hold on wood.
Gelcoat on epoxy is not possible and would be not sensible too.

Fairing and painting is the method on a sheathed hull.

On a GRP repair again epoxy is the material of choice, because poly does not stick on poly too! At least not sufficient.

Now, why would one apply a weak material (gelcoat) over a strong one? (fortunately it is not possible to make that mistake. As mentioned Polyester does not stick on anything except uncured polyester.

Result:

go for epoxy in both cases, fair and paint it, and save a lot of time, money and hassle.

And always do the opposite of what tunnels recommends, he does not know about this stuff!

Regards
Richard

[CDK]

The Balkan style to coat wooden boats is with polyester and talcum powder. Adding it to the resin in large amounts until the paste has the consistency of butter, it is used as a filler to replace rotten wood. Then they laminate 2 layers of glass cloth and finish the job with another thick layer of talcum powder resin that serves as a gel coat.
The serious guys sand it flat and paint it with "Veneziani Gel gloss" which is a 2C polyurethane paint, the majority doesn't care about cosmetics and goes fishing as soon as the resin has set.

[TeddyDiver]

Originally Posted by CDK

The Balkan style to coat wooden boats is with polyester and talcum powder. Adding it to the resin in large amounts until the paste has the consistency of butter, it is used as a filler to replace rotten wood.

And wheat flour works too to same purpose..

Turks use plaster! Works perfect for one summer.

[CDK]

Originally Posted by apex1

Turks use plaster! Works perfect for one summer.

Which makes talcum powder a better choice Richard. It is magnesium silicate, much more durable than plaster.

But it also has a disadvantage: female passengers should wear underwear at all times!
Google for talcum and you'll find this:
"Researchers have found talc particles in ovarian tumors and have found that women with ovarian cancer have used talcum powder in their genital area more ..."

What do I care about turkish fishermen Cornelis? That became a third world country after having been part of civilisation for ages.

[ondarvr]

If you want more info on the original question.

Gel coats are formulated in white bases and neutral bases, actual clear gel coat is a different formula. Neutral may be what he calls clear, its normally a dirty grayish color, but in a thin film may be somewhat clear.

Whites bases are used for whites (obviously), off whites, pastels and blended with neutrals.

Neutrals are used for colors.

Not every color can be matched by using only one base (supposed clear this time), the reason is frequently too much pigment needs to be added and it can create cure and spray problems.

Adding pigments will change the gel time, viscosity and other aspects of the gel coat, these changes can be from not noticeable, to making the product unusable.

As for wax, use it only in the final layer of gel coat being used in a non mold application.

Talc is a poor filler for products being used under water, it will absorb water which can change the color of the gel coat or resin and possibly cause it fail when used as a fairing putty.

[TeddyDiver]

Originally Posted by ondarvr

Talc is a poor filler for products being used under water.

Talc is ok, doesn't atract water any more than the poly itself .
Cement (portland) is also possible if you want somewhat harder and a bit fire retardant mix.

ps. a link to home brewed mold gel http://www.rcgroups.com/forums/showthread.php?t=1131024