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Sticky 03-05-2007 03:33 PM

Casting Parts from Print a part masters
A friend of mine is having some issues making molds from printapart masters. He says that the rubber won't set where it contacts the master. Has anyone else had this issue or can they suggest a material to use. Thanks

David Diaz 03-06-2007 08:11 AM

Hello Sticky,

This seems like an issue of incompatibility between the material of the master and the rubber he is using. Or the issue may well be the rubber itself. Maybe the rubber is not mixed thoroughly or maybe one of the components is old and not working properly (This has happened to be) as mold silicone rubbers have a very short shelf life.
Find out what kind of rubber is your friend using? In what kind of proportions does he uses the rubber? Is he using a mold release agent?
Find out as much as you can, Iím sure we can find a solution.


Alasdair 03-22-2007 01:37 PM

Need a isolator primer
The type that you get from Car (Classic) paint shops. Very thin and designed to prevent chemical reactions and "leach thru".

Buzz me on Yahoo if you need help finding the right stuff Sticky. AMPS this year mate ??


Sticky 03-22-2007 05:48 PM

Kewl beans, will do. Yes AMPS for me this year!

Alasdair 03-23-2007 11:41 AM

Cool, see ya there John
Hope Grumpies will be fun as Kids singing badly :)

fantacmet 06-13-2008 07:14 PM

If you haven't found an answer yet, give Tap Plastics a call. They can help you find a solution. Part of the problem might be, that when made these things are supported by wax, and they dip them in molten wax to remove the wax support. So there is still a wax residue of some sort. Tap has a silicon mold product that is really nice, and they do mail order as well as in store. I'm lucky enogh to have a store near me. The nice thing about the mold material from them that I use, is I don't need a mold release agent. Either from the master or from the part. Which saves a boatload of time.

MCR 10-03-2008 02:41 AM

The problem may lay with which type of rubber is being used to make the mold.
The two main types of silicone rubbers I know of use either a tin or platinum based catalyst.
I know from sad experience that platinum catalyst rubber (Silastic J for instance) does not like certain common glues we use in the hobb, especially CA glue (super glue).

A suggestion would be to switch the type of mold making rubber being used to a different type OR to put a thick layer of primer over the master and allow it to cure for several days before trying to make a new mold.

Good luck!


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