well i know that plastic does NOT react well to tooling gel coat. so i sprayed 4-5 layers of PVA. let it dry. sprayed the gelcoat, layed up my csm and took it out of the mold. the mold is ok, i fix it by wet sanding… but the part had tiny bubbles now b/c of the gel coat. i dont want to mess up the next piece, will partial wax be ok to aply on the part before hand and THEN spray pva on it??
What type of plastic are your plugs made of? Typically PVA is enough of a barrier to prevent any reactions with the plastic. However, sometimes, plastics will deform from the heat of curing.
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Use more time inbetween the gel coats and lay ups as mass equals lots of heat!
im doing 1 layer at a time. theres very minimal heat.
If you are making a mould from a plastic part, why not use epoxy resin system, with powder bound CSM for your mould?
Its more expensive, but you would have no problems with adverse reactions, and as soon as you have a good mould, you could make a CSM master plug from it, if you needed to make more moulds.
that sucks it did not work, I am just finished a mold off a plastic piece and it worked perfectly fine. I used TR High heat wax, like 8 layers lol but it worked perfectly fine hmmm…
What is the plastic code on the inside of this piece?
Is this plastic piece being used for the mold or as the plug to make the mold? Once you have a extra thick, perfect part from the mold just keep that as your master plug to make another mold if needed.
Totally agree.
Seeing as how polyethylene is a release agent for epoxy you win both ways by usinng it. I guess thats if your plastic part was made with polyethylene.
If the part was made out of polyethylene, there sould have been no reaction at all. The Airtech red flow media and (rigid) resin infusion lines are both made of polyethylene.
its abs plastic =(
If your are having problems with reactions, use epoxy, and save yourself a lot of time and extra unneeded work.
all of the motorcycle parts I work with are ABS plastic. I don’t have any problems with bad reactions. I did once, when I first started. I solved it by applying the PVA properly. I don’t know how thick of a layer you’re applying, but I shoot for about 3 mils which is very thick. That is the thickness of the heavy duty contractor trash bags. Try that and you should be fine. Also, are you sure the resin is reacting with the plastic or is it reacting with the paint on the plastic? Gelcoat is a very good paint stripper.
Agree entirely…most bike plastics are painted, and if you are trying to make moulds from painted parts, that may well be causing your problems.
Thing is though a painted part with decals etc, is going to provide a mould which needs a pretty fair amount of work before its usable, so might be worth thinking of surfacing painted parts, with something smooth enough to take a good mould from, without having to worry about decals, paint etc?