Castable clay

Bob,

You will need to make a plaster mould of the tile form, as clay slip
won't dry out successfully in a rubber mould.

Make a plaster tile from your rubber mould and don't let it dry out!

Get some Soft Soap (also known as Mould Maker's Size), and using a soft
brush and a little water, work up a thick lather and coat the surface of
the tile with it and let it set. Keep coating and re-coating until the
tile surface is very slick indeed.
Place the sized tile face up on a board (a piece of Melamine faced board
is ideal), and seal where the tile and the board meet with clay so that
plaster won't run in underneath the tile.

Build a clay wall around the tile at least 1.5 inches away from it and
the same height above it.

Mix up enough plaster to fill it up. Try to mix it up as gently as
possible to avoid trapping air in it, and pour it gently down a ruler or
similar into one corner of the walled area so that it floods gently over
the tile. When it is full, gently bang the board for a few minutes to
jog any air bubble in the mix up to the surface, and then leave it to go
hard.

The Melamine surface of the board won't allow you to lift off the cast,
but you should be able to slide it off sideways.
Stick something with a strong point into the back of the plaster tile
and see if you can prise it free. Do this gently as well because fresh
set plaster, although apparently hard is quite soft until it has fully
dried out.

When the tile is out, set the mould to dry thoroughly before attempting
to use it.

To cast from it use Casting Slip which contains relatively little water
compared to clay and water slip and so won't over-wet the mould.

I apologise if these instructions are overly simply stated, but I find
it is best to assume no knowledge, unless you know fully who you are
trying to help.


Steve
Bath
UK


In article , Bob
writes
What type of clay and any other materials do I need to buy to make a
pourable or castable clay ?

I have a rubber mold that will produce a tile about 8" X 8" X 3/4".
The finished tile is a relief rather than being flat on the face. The
tile will be glazed with different colors. What do I need to make a clay
casting of this mold ? The finished pieces will be used as wall
hangings.

Tampa Bob

--
Steve Mills
Bath
UK

I think that was a great description! Short and to the point.

I have saved it in my pottery reference folder.

Thanks!

Marianne

In article , Bob
writes

Make a plaster tile from your rubber mould and don't let it dry out!

Why do I not want the plaster to dry out ? Also, how do I accomplish
this ? How much moisture in the plaster is "not dried out" ?


You need the plaster tile to remain damp, as this prevents the Soft Soap
from soaking into the plaster. The function of this material is to act
as a release agent, so if it soaks in it won't release the tile from the
mould!
--
Steve Mills
Bath
UK