Casting a Plaster Copy

[Junkie]

Hi,
I want to cast a copy of an action figure. I want to cast it in plaster. What do I make the molds out of?

This will be a one time only thing and I don't really want to use RTV Rubber molds if I can help it. Too expensive.

Any ideas? Can I use a plaster mold and cast again in plaster?? Lots of petrolium jelly as a release agent maybe.

Thanks
Scott.

 

[Elm City Hobbies]

I have only used RTV molds to recast plaster. I am sure there are probably other ways, and if it is a one off, then it shouldn't matter much.

Only thing about plaster on plaster, it will stick to itself quite readily, and I think something like petroleum jelly would fill in he detail a little to much.

Wax would work, would still have to be a 2 part mold for a figure. Not sure what kind of wax mind you....

 

[JMac]

RTV can be kind of flexible, a big plus for revmoving the master or the cast part from the mould. I've tried to use plaster to make a simple mould of an aluminum part, didn't work out so well, broke the mould geting the original out.

 

[Junkie]

OK. Guess I should use the RTV and then pour plaster.

Do y'all think I can use normal release agent when pouring?

 

[Elm City Hobbies]

With the plaster in RTV, you don't really need a release agent.

Good tip...once you pour the plaster in the mold, sneak away to the dryer, place the mold with the plaster on the dryer and run it for 10mins or so. The gentle shaking of the dryer will vibrate the air bubbles out of the plaster. Works with resin as well, just don't let your wife catch you near the dryer, or she might put you to work doing laundry!

 

[Junkie]

Great tip. Today's molds will be ready tomorrow afternoon. Can't wait to see how the first pour turns out.

 

[Little Cutie]

While I was editing this post - you chimed in, so it deleted my entire message before I could post it. Oh well, here's the link that I was looking for. I hope this will help. I was going to suggest using a tube of silicone caulk, then filling a mould box with this, then submerging your part in it half way. Then letting it dry. It'd probably be a good idea to spray it with Pam, or some other type of non-stick cooking spray. Then make a reverse mould as shown in the video. You can pour whatever type of resin into it afterwards to make multiple copies.


How to make a two-part mold

 

[ScarredKustoms]

I do a lot of mold making for my one company, RDF Squared LLC, I pretty exclusively use smooth-on products. http://www.smooth-on.com/ They have great tutorials and excellent customer service. Anytime I have had a question I just call them and they have an expert walk me through what ever it is. Actually I call my local distributor. http://www.tfbplastics.com/

You could have done a plaster mold but would have been a pain. Silicone is the best route for most applications. Only time I use "plaster" is for special effects appliances and mask making.