Making mold for clay mosaic base

[clyoung]

Hi,

My friend makes mosaics.  He makes small cross mosaics (around 3"x4") and other shape mosaics (like veggies and such).  We are trying to find a way to make molds for these shapes.  To be more specific, we want to make molds for the clay bases that accept the tiles.  He currently hand cuts/carves each one.  We used plaster as a mold which required that the casts coming out of the molds be tapered which in turn made the clay base shapes become distorted (biggest problem is we lost the hand-cut edge details) and loose that hand-crafted look.  I was thinking about some type of two part mold or a rubber mold that would allow the hand cut shapes to keep their edge details.  Does anyone have any thoughts on this?  We can make our own molds or we would like to find someone who would manufacture the casts/copies for us.  We don't have to use clay but would prefer to stick with something more natural like concrete.  Thanks for your help!

-Chris
 

[Lady Rando]

Here's a link to my tutorial on making a latex mold. I cast in hydrostone whish is a gypsum cement so you should be able to adapt this method to casting cement.

http://www.ehow.com/how_4808181_cast-gargoyle-sculpture-other-sculpture.html