Epoxy/ Poly Resin and Fiber Glass

[james17]

Our team is getting ready for a our first shot at fiber glass bodywork and i have a quick question or two to make sure we get it right the first time. We are using an MDF/poly-foam male mold and 2-ounce fibre glast (sp) cloth. I know normal poly resin will melt the foam, so we have epoxy resin. Is the best method to lay the epoxy resin down as a sort of mold release and then use lay the cloth and poly resin over that, or can i make the first layer using epoxy resin and then make the next two layers using poly resin, will they bond together? Also, does 3 layers sound right for 2 ounce fiber glass cloth for side pods and nose section. Thanks

James Higdon
SAE@UTSA Cheif Tech. Dir.

[james17]

Our team is getting ready for a our first shot at fiber glass bodywork and i have a quick question or two to make sure we get it right the first time. We are using an MDF/poly-foam male mold and 2-ounce fibre glast (sp) cloth. I know normal poly resin will melt the foam, so we have epoxy resin. Is the best method to lay the epoxy resin down as a sort of mold release and then use lay the cloth and poly resin over that, or can i make the first layer using epoxy resin and then make the next two layers using poly resin, will they bond together? Also, does 3 layers sound right for 2 ounce fiber glass cloth for side pods and nose section. Thanks

James Higdon
SAE@UTSA Cheif Tech. Dir.

[Dr Claw]

is your mdf/foam buck sprayed with primer? with a decent coat of primer (then mold release), it doesnt matter whta kind of foam you use..

*edit* just make sure the primer doesnt eat your foam

also, dont forget to sand the primer until you can see yourself. thats arround 1500 grit.

[james17]

Dr., we've used primer with mold release over it before and ended up having to use hammers and screwdrivers to break the bonded on mold release and primer from the back of the glass. We've got the epoxy resin which we have experience with and i was trying to avoid another mold release disaster. When we did try the mold release method we used both proper mold release and full latex paint, any body have something specific that works better?

James Higdon
SAE@UTSA Cheif Tech. Dir.

[Tony K]

WaterWorks mold release. We use it on all of our composites tooling and molds, and it's magical stuff. We coat the surface of the part tool with spray bondo (as most paints soak into our tooling foam too much), wet sand to a smooth finish, and then apply the mold release. As long as you follow all the directions, there should be no problems whatsoever.
WaterWorks Aerospace Release System (http://www.waterworks4.com/english/index.htm)

[Dr Claw]

so...what kind of mould release are you using? also, if the PRIMER comes with the mould release, then it seems to me that you've used the wrong primer being that it let go first. i've never used latex primer either, i usually use a polyester, or vynl ester primer. basicaly an automotive one sprayed from a semi profesional sprayer. just make sure your foam wont get eaten by M.E.K./zylene/toluene as they are used as solvents for the paints. if your foam is totally coated with bondo on the other hand, no need to worry as your foam proved it'll stand up to the solvents (and besides, its all covered anyways). spray away. and then use PVA. if your still stuck with PVA, you might have too deep of mould draw, or your in mould lock to begin with. PVA, when you spray it and totally coat your surface (a surface that you've waxed 2-3 times), it is garanteed to work.

[Erik Whoa]

I agree with dr. claw. Use bondo and make sure the PVA is a fine mist. 2 oz glass seems kind of light, especially for only 3 layers. Last year, we used 9 layers of 1.5 oz and it came out thin and very flimsy. We then had to repair it and it became more trouble than what it was worth. if you use the 2 oz I would use 13 or more layers. Are you vacuum bagging it?

[james17]

Is this the part of FSAE that is supposed to be fun? The members of our team currently active have never done glass before, we were told our 2 ounce glass was a "special glass" and would be stiff in only 2 layers if we used epoxy resin. Well, "13 or more layers" is starting to sound more like. Also, despite the info provided here due to our previous failures with mold releases we ended up going with a lost foam/epoxy resin method. Has anybody done this with any sucess at all ? Thanks

James

[James Waltman]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by james17:
Is this the part of FSAE that is supposed to be fun? </div></BLOCKQUOTE>

We started getting tired of composites work when we were doing layups all summer long to make Viking 32 (http://fsae.com/eve/forums/a/tpc/f/648600998/m/74010383211/r/74010383211#74010383211) .

We mentioned this to Dr. Seal, the founder of our Vehicle Research Institute. He told us something like: "There are two types of people in the world: Those who don't know how to do composites work and those who know better"�.

Really though, once you get the hang of it things get better. About your original question. I wouldn't mess around with mixing epoxy and polyester in a laminate. If you are having trouble with mold releases you should try a flat laminate that uses the same materials and processes.

[Sarsippius]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">part of FSAE that </div></BLOCKQUOTE>
The shape of your mould is going to be a consideration too, the glass will shrink a tiny ammount and clamp onto the mould. its kind of like glassing up 3/4 of a tennis ball and then trying to pull the ball out through the hole, well you get the gist, just be aware of curves that come back on them selves, like the side pods or fance nose cones, then its not a bonding issue, you can have all the release agent you want, you are going to have to still pull it off. But thats half the fun working out how fix your f*^k ups.
All the best
Sarsippius