(05-20-2010, 11:17 PM)modelnutz Wrote: B-man...the short answer to your question is.... yes, you can cure a mold under pressure and yes, you will get a decent mold...as a matter of fact, the mold will actually have better strength properties due to the simple fact that the molicules of silicone are packed a bit tighter together. ( higher density = higher strength )
However... ( doesn't it suck that there's always a "however" to these things ? ) if you do pressure your molds...your masters had better be very solid items....ANY air spaces that have the tinyest openings will be completly filled in the process. ANY porosity of the master will cause the silicone to lock in to the master ( ask me how I know
Also, if the silicone is not FULLY CURED, you will have a real fun time watching the air bubbles expand inside your newly poured mold.
( again, ask me how I know)
So, to sum it all up...yes, it's possible....but it's a much more certain outcome to vacume de-gas a mold.
Thanks Man . I'm always trying to find the fastest and "Cheapest" way to do things. If I could use a pressure pot for double duty, that would be great for me. Of course cheaper, can mean you have to Vac degass and pressure pot your parts. Other wise you spend the money in bad parts, i.e. wasted material. I'll probably give it a try, and if it doesn't work, I'll go back to the tried and true. I am always willing to earn from others mistakes as well. I mean that's what these forums are about. You guys know your stuff. I'm just a beginner in some of these processes. I've done everything you can do with fiberglass and composites. Including building Minesweepers for the Navy, but haven't used Silicone yet. The only molding I've done, is with Frp, and plaster. Used latex once or twice. So I defer to the collective wisdom,
I know one thing. I've learned more in a few years on forums like this, than any where else. So thanks again, Cheers,Joe
(05-21-2010, 05:34 AM)427 Cobra Wrote: That's another reason why I wouldn't trust pressurising the mould material, just for safetys' sake! Most people make two part moulds that are hollow and don't have the durability that I incorporate into all my things. I want durability, which is why I'd just use an epoxy fibreglas mixture for the product, and forget about pressurising, or degassing the mould entirely.
What are you trying to make with this, if you don't mind me asking? I mean is this a two part mould, or is this a really big solid part that will need two sides to complete?
~ Cobra Chris
Chris, the original question was about general parts molding. Like casting kit parts and such. On my bigger parts, I plan to roto cast, so it's not so much an issue on those. If I don't have any undercuts on my large parts, I can probably use a fiberglass mold. I had read somewhere that you could pressure cure the silicone molds, thats where the original question came from. I think the majority of my parts, will be open faced molds. I have a lot of small parts from kits to make duplicates of. We'll see how it all works. As soon as I get my supplies, to finally start doing this stuff, Cheers,
Joe