Multiple Cavity molds

[snippp]

As a learning lurker here I appreciate all the knowledge shared.

I have aquired some fiberglass molds, Lee's pots, etc. and wish to make some different molds from fiberglass resin. After makeing the original 4 cavity mold useing resin, what substance is used to make the "master" to make more resin molds from???

I have used the "search" and cannot find the information.

Thank you,

Snippp

[redg8r]

since youre using poly resin as the production mold, Id recommend using silicone rubber for a mother mold.

RTV silicone will reproduce a perfect negative of your existing mold.

when you need another production mold just pull the mother mold out & cast your poly resin into it & you should be good to go.

I have a few that way, if you need a pic lemme know & I'll go snap a photo of one.

I know some guys who use silicone as a production mold will use poly or urethane resin as a mother mold.

[snippp]

Thank you for your help. I will give it a try. Any secrets that you have found work the best?? I want to try and prevent any air bubbles that will affect the final mold.

Snippp

[redg8r]

the best thing Ive found to prevent air bubbles on the cavity is to brush a thin layer on the surface before you pour. that goes for just about any molding medium.

good luck w/ it, its fun when you get the hang of it.

[Mojo]

Red, are you applying a vacuum to your RTV after mixing to get the air bubbles out? The web sites I've read say to put the mixed RTV in a vacuum cabinet to get rid of the bubbles that accumulate while mixing.

I have a vac pump, but don't want to build a cabinet unless it's necessary.