Hi there, ive been making carbon fiber parts for a while now with just a wet lay up, and have been experimenting with a few different things. recently I ordered some 70-25 Tin-Sil RTV Silicone Mold Rubber from a company called ILLSTREET composites. and I if you guys like it? if its good with Infusion, and whats the best releasing agent/wax for the plug and for the epoxy?
Thank you!
1: depends on your part, depends on whether silicone molding will be right for you. I have done it in the past, and it kinda worked.
2: just the part name reminds me of PolyTek’s silicone molding rubber…I’ve used it many times and as long as it’s mixed, and degassed, it’s a good product.
3: You should NOT need a mold release with epoxy and silicone. However, it never hurts to use what they recommend in case. Never had a part stick to silicone, however I have had silicone stick TO a part. i used Henkle’s Frekot, which i understand is NOT a release for silicone, but a glue!!!
4: You will want to make sure your mold, while under vacuum does not deform!!! Silicone is soft, and might distort under the vacuum pressure!! You can deal with that by using a solid mold backing, or a very tough shored silicone.
Thanks dude! your the man! I have been road racing for several years now and im tired of buying xxxxty poor fitting parts that are heavy or poor quality, so im gonna make my own. what type of backing do you recamend?
I think http://polytek.com (Polytek) website has a lot of tutorials. ( http://polytek.com/catalog/catalog.pdf ) I think a simple fiberglass/resin, or 2 part plastic, or really anything that can be a hard shell, that conforms to and gives structure to the silicone mold.
Some people also make the mold casting thin, and add 1+ layers of a THIN fiberglass layer, so the silicone doesn’t rip, and might not compress as much. Chopped glass would work as well as fumed silica (cabosil, et al) will give a harder density to it. Sometimes you can get away with making the whole mold from that, othertimes it’s safe to case a thin layer on your part, and back the silicone up with the denser/strengthen stuff.
What kind of parts are you planning on making? If large pieces, like body panels, dashes, wings, are being made, it might be safer to make a tooling gel/fiberglass mold.
just air dams, headlight deletes, canards, mirrors, things of that nature but eventually i would like to make some splitters and defusers. But i think i will lay my silicone then back it with plaster or a fiber glass back for now. my silicone will be in some time this week, mabe i will do a write up. whats the best way to de-gas it?
Why not use a tried and tested gelcoat and fiberglass??
silicone smells better 
falls over
Go with either gelcoat/PE or VE, or surface coat and epoxy for mold construction.
Hojo why would you suggest a gelcoat/pe or ve over the silicone tin? because there is no need for backing the tool?
Its a standard for creating tools for your application. It will be durable and last a long time, the surface will not distort. Why do you feel a silicone surface would be better?
Because I can make a 0.5mm thick (or less) mold with the sylicone then back it with plaster paris. and not have to use as much releasing agent and not have to keep diffent kinds of PE and PV’s for the molds and epoxies for the fiber. just less supplies i need to keep around. Just my thinking… Please correct me if im wrong or dont make sense.
Makes sense. Always a fear of having a part/plug stick to the mold, or bubbles in the tooling coat. Been there, done that. Silicone is perfect, except for the fact that it’s soft and can warp/compress. However, for this project, I doubt you will have issues with a little misshaping. Silicone is expensive though.
Plus later, you can carve a design in the silicone and have it transfer to your blade!