using clay to make a mold box?

[Sulla]

Is it a bad idea to use clay as a box for making a small one part mold? Say 6cm x 9cm x 2cm deep?

 

[madrobot]

It can be, if you are making a 2 piece mold.

 

[Sulla]

It can be, if you are making a 2 piece mold.

nope, just making a one piece mold.

 

[madrobot]

So long as you're careful about the thickness of the clay wall, and make sure there's no holes for the silicone to get through, you should be okay. I personally would rather use foamcore.

 

[foxbatkllr]

I've used clay as a moldbox for a really small funny-shaped part before. It will work fine and saves you the trouble of making a more elaborate moldbox.

 

[Sulla]

Thanks all. I found an old plastic container that I just cut the bottom out of and mounted on styrene using clay around the bottom to seal it.

It is my first cast of anything ever. A fun little project. I'll let it cure overnght and see how bad a job I did. I never count on my first attempt at anything in the world of props to work out the first time around.

 

[replicaprops]

Make sure you put release on the clay, and dont use water based clay.

 

[exoray]

I personally would rather use foamcore.

I second that foamcore, a hot glue gun and a little tape makes quick and clean work of molds...

But, clay will work just fine as well...

 

[replicaprops]

I use sheets of acrylic. I cut them to any size I want on the saw then hot glue them.

I used to use legos, but the larger molds alway leak.

The best part about using acrylic is you can use it again as a mother mold and if you spray ease release on the acrylic, the resin drips flick right off.

 

[Reactor drone]

I've used clay and plasticene for small items,especially strangely shaped ones.

Make sure it's non sulphur or it might inhibit the cure of certain silicones,if in doubt a coat of spray wax,latex or PVA glue will provide a barrier but I've never had a problem,even with toystore plasticene.

 

[Sulla]

Thanks for the tips everyone. Here are the results: http://www.therpf.com/showthread.php?p=677163#post677163