Resin: what is the best mold and filler

You can get either RTV rubber or Silicone for molds, I have used both.

As for resin this wil depends on what properties you want during the casting process and in the finished piece.
i.e. curing time, hardness of the part, etc.

There is no single resin that does it all shape, size and your mold design will also affect the choice of resin and it's curing time.

Alright cool thanks. Gives me a better understanding of what I am looking for.

Has anyone tried that One-to-One mold making and the CR-300 CASTING RESIN. I saw it at micromark and seems like the stuff that I need.

I'm using the One-to-One RTV molding material and the CR-600 resin. I'm having very good luck with both but I'm looking around for a cheaper product that has the same performance. MicroMark's price on resin products is a little steep for production casting.

The last time I bought silcone rubber, it was a 5 gallon bucket from Goldenwest Mfg. It was great stuff. I used tons of their R1 Fast Cast resin also. It is basically the same as Alumalite.

You can get a good price on rtv in bulk and it will last a good while. Just dont let it freeze.

If you get larger quatities of a/b casting resin and live in an area with high humidity, make sure you get nitrogen spray to fill the void in the bottles. The brown colored part of the resin will suck water out of the air and cause bubbles in the cast that vacuuming wont take out.

I was able to make a nice little vacuum chamber for small parts with a bell jar and a brake line vacuum from an auto parts store. It would pull 29 cfm once you pumped it up. I used it so vaccum the container of rubber before I poured also.

Side note- If you use non harderning clay to make a master to mold, make sure it is sulfur free clay. The silicone will not cure where it touches the clay.

I've had very good luck with the standard automotive firbreglass resin you find in an auto supply store. Tried Alumalite but it dried way to fast for my taste. I prefer to have a little time to work the bubbles out of the mold before the resin sets up.

Hi, I have tried few resins, polyester type (use in automotive and nautic), urethane and epoxy. As I live in Buenos Aires, Argentina, I can get in the market only polyester and epoxy. To make my models I use the polyester type, with different results . Tried urethane and work great, Now I`m using only epoxy, produced here in Argentina (according to the salesman), and you can`t tell the difference between a bougth model and one produce by my hands, in texture, smoothness, colour, etc. I´you live in USA, try this site http://www.synair.com/ I bougth from them urethane and RTV rubber and the special release agent (be carefull as this stuff eats stirene plastic). Also try Micromark they have some stuff.
To Hatewall, maybe you can give us a picture or diagrams on how you made your vaccum chamber: I`m making my own, and maybe won`t make mistakes.
JGM