Fiberglass and mold making question

[pitchforknumb]

That is why I have sprayed my gel coats... I can do an entire body.. Standing up...all at once... Gel application time about 30 minutes for the whole mould.
Not one pin hole or bubble due to the spray application.
No need to even think about gravity due to the spray application.
It is a nice technique to have.

When you say you've sprayed your gelcoats, was that with an airbrush, or am I totally off track?

And for the hardener, you can use both, but I just use the resin hardener, and double the amount I usually use.

 

[Dr Know]

A little off track...
Gel Coats are a bit too viscous to go through an airbrush..

Some HVLP guns ( high volume, low pressure ) will run straight gel coat fine... For some, you may have to add a little acetone , or styrene monomer to the gel coat to thin it out a bit. Around 6oz acetone per quart of gel... Catalyzed at 1.5% by weight of the gel using the MEK-P. That is for a 72- 75 degree room "Fahrenheit".

PVA is always a great release... And easy to use... Water based for easy removal from the mould as well... And as mentioned before... Protect one self with the proper gear... Respirators and Tyvek suits...

When using Gel-Coats, you must learn to let it set up all the way. It will squeak under your finger when it is ready... Like a windshield wiper on a dry window. Then laminate.


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[clayslinger]

I had some of these same questions and Fettster was kind enough to educate me in his fiberglass method using gel coat for his molds over his super detailed water clay bust sculptures.
He posted it in his Daniel Craig sculpture thread. VERY helpful and I'm grateful for his help!!!

In the states, U.S. Composites has tooling gelcote in black and orange as well as tooling laminating resin for super reasonable prices per gallon.
They sell in quarts too.
They also have gelcoat dump guns for spraying.
Equipment

I've used them for years for mother molds but never a mold for silicone skin. The cured surface of tooling resin is plenty hard enough and the consistancy is not to thin and not too thick when brushing on.

Hope this helps!
Chuck...

 

[Dr Know]

Nice link...
I like those guns as well, though they are a bit more involved when cleaning up... They do work well.
Tooling resins are nice, and better with heat... In case people are considering baking their mold in ovens and foam latex castings.
The styrene monomer will be a little less than a normal ISO laminating resin... So one may find the lay up a little easier to pre-wet the laminating layers prior to applying the matte to the mold.
Laying out a piece of aluminum foil... And wetting out the matte on the foil first.. Let it sit for around 30 seconds... Then apply the wet matte to the mold. This will help the removal off the air bubbles during the lay up process.
I also use a roller on my glass work. Works really well, re-usable.. And saves a lot of money own using less chip brushes.

One thing to consider... If you do plan on casting a silicone skin out of a fiberglass mold... Be aware that some additional cure (platinum) silicones may be sensitive to the styrene in polyester ... There are products like "inhibit x" from smooth on I believe that work really well for these applications. But if you use a "tin" silicone... You will have no need for the "inhibit x".

Happy New Year people...

 

[gmont]

isnt there a link to where it says the different options of molds/castings to make a fiberglass part?

im thinking about using an expanding resin foam to make my mold and just thought is it going to melt or something getting mixed up with the fiberglass resin?

 

[v3d]

You could add a filler like Cabosil. It looks like white powder and thickens fiberglass resin. You do need to wear a respirator when using since it is non organic and will build up it your lungs if you breath it in.