I am wanting to make a mold with a painted part and would like to do so with out having to repaint the original. Any ideas appreciated. Thanks GE
Apply PVA. No guarantee for success, but it is your best bet if you do not know the paint used.
Thanks for response. Tried that with side covers before. Didn’t get results I’d hoped for. Is there something besides fiberglass I could use for mold? Thanks again.
This can be very tricky. Usually a coat of wax and then PVA. Unless you are flanging the part you will get resin around the edges and then when you are grinding the mould trying not to hit the edges or chipping them is difficult. The other problem is the not neccicarily knowing the paint on the part. I did a 1970 GTO body many years ago and it had an early version of urethane paint on it and it wrinkled the entire surface. Not sure what reacted but was a total cluster xxxx. Not sure if it was a chemical reaction or the heat of the laminate curing that caused the problem.
Now I just resign myself to the idea that the part is going to be repainted.
What results are you looking for? PVA is the surest way to prevent problems with the substrate although I’m not dumb enough to guarantee no problems. Just gotta make sure you get enough on to create a good barrier.
As for Ditchdogger’s comment about no flanges, I’ve had good luck in the past just by applying masking tape to the edge and not wrapping it around tight to the donor part/mold. The tape will leave a small depression along the edge of the part but I was post-mold finishing anyway so it wasn’t a bother.
Was hoping to not harm the paint making the mold basically. I waxed 4 coats,PVA,gel coat then fiberglass on side covers before. When I pulled it apart the paint blistered. Was just hoping to avoid that on this piece. Different bike but same paint,ppg w clear I believe. A sponsor does the paint work for me. Didn’t want to make more work for him if my piece doesn’t turn out. Thanks again all.
How did you apply the PVA?
I dumped it on and evened out w a rag. The piece came out of mold nice but paint was blistered.
Did you see any significant heat from the exotherm? Maybe that is the cause of the blisters. Either heat or you didn’t really get a good barrier film built up. I prefer to spray the PVA in multiple thin coats to create a good film.
I believe it was heat. Didn’t know if there were more options other than fiberglass. Thanks all
There are lots of different options for making a mould, it just depends on your budget and how serious you want to get!
For example you could use a casting system, either silicon or something like dental alginate to create an initial mould - then cast the shape using a suitable material that will be hard enough to support a composite mould, and ideally not chemically reactive with your composite materials.
Perhaps you could even use plaster, and just spray it with some kind of sealant before making a composite plug?
Strange that your 2k painted part (that’s what it was, right?) reacted with the blisters. But if you can’t reduce the exotherm (can you do one layer at a time and wait for it to b-stage before continuing?) then check out the body casting materials - they ought to be much less harsh as they have many options that are suitable for body casting, direct on a persons face etc.
Actually one more option I just thought of - you could probably also create a vacuum forming rig and create a mould from a sheet of perspex.
[ame=“http://www.youtube.com/watch?v=KfZFw2zc3sc”]DIY Vacuum Forming Machine 3mm Acrylic Sheet Prototyping Shop Built Home Made - YouTube[/ame]
There’s always lots of options…
Exellent information sir thank you.