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A caution for CAD/CAM artists

This weekend, I was putting together a little project using a
Perfactory produced model. It was beautiful. There was no way that I
could have done as well by hand. I was running short of my silicone
from Zero-D, so, since I was in a hurry, I used the Costaldo
LiquaCast that has been sitting around for quite a while. Big
mistake. The “rubber” bonded with the model. Both were destroyed
while trying to cut the model free from the mold.

I have since been told, that a silicone, teflon or vegetable spray
would have made a barrier for the LiquaCast.

I like the fact that LiquaCast isn’t as messy as the Zero-D that I
usually use. It also seems to be a little tougher. I don’t like when
it bonds to my model though.

Different releases are needed for different mold materials. Silicon
vaseline, releases stating “release for silicon”, Teflon, soap etc.
A release of silicon will NOT release silicon mold materials.

Many of the label/instructions that come with different mold
materials do not make this point clear which is unfortunate, but
many folks don’t really read the instructions anyway and just how
much reading “material” can be reasonably packed onto the
instruction sheets. Can get sort of like the “fine print” on many
of the things that are passed to use with a “Sign here” statement
that we don’t read as it would take a half hour to do so and then we
wouldn’t understand the fine points anyway…

Sorry for you problem on the piece.

John Dach - been there, dun that!

Guy, I only use the Zero-D Clear silicone RTV because I never have to
worry about it adhereing to printed or other generated models. I read
the msds for the Castaldo Liquicast and it contains mercury compounds
which are bad for your body, but are also a problem in landfills. I
stopped using it.

I don’t know how damp it is where you are, but over time the
Liquicast urethane mold may become gummy and sticky and useless.
Silicone molds will last forever.

Good Luck,

On the subject of releasing silicone mold materials –

I like Castaldo’s Mold Separating Cream. I put it on the edges of
the mold frame. I don’t think that was their intention, but it

I also put super parchment on the outside of the mold frame, on top
and bottom, as it were. What is super parchment? It’s this Teflon
sheet that is sold for use in home baking. It keeps your cookies
from getting stuck to the cookie sheet. Works great for that.

When you’re done vulcanizing, just peel back the super parchment!
No sticking. Saves time.

Where to buy super parchment? Up scale kitchen shops or specialty
stores. Williams Sonoma has it. Sometimes you can find it at Bed
Bath and Beyond or Whole Foods.

You can also get it from me, by the way. (and for less than
Williams Sonoma.)

Elaine Luther
Metalsmith, Certified PMC Instructor
Hard to Find Tools for Metal Clay