Ceramic
Molds - The beginning
To begin the process of creating
a piece, the clay must be prepared and shaped. To do this,
a mold is used. A ceramic mold is a hollow, plaster form
in which pieces are reproduced using liquid clay, referred
to as “slip”. Molds are constructed from plaster
which results in the mold being porous. This is important,
as the plaster walls of the mold absorb water from the slip,
producing a clay shell. A mold can be comprised of one piece
or many sections that are held together with thick rubber
bands or straps. Molds are usually plain on the outside,
as it is the internal part of the mold that determines the
shape of the finished piece.
Every mold is different and complex in design. Each
mold can contain more than one opening. These openings
are called pour holes. This is where slip or liquid clay
is poured into the mold. This process is called casting.
During casting the slip is carefully poured to fill the
absorbent plaster mold, allowing enough time for the clay
to build a shell against the walls of the mold. When the
desired thickness of the shell is achieved, the excess
slip is then drained and the soft interior clay shell
is left to set.
When the shell inside the mold has set and can support
it's own weight, it is then removed from the mold. Both
room temperature and weather conditions have a significant
effect on casting. For example, if it is raining and the
pour room is cool , it will take longer for the mud to
set in the mold, however, if the pour room is warm, the
casting process moves much faster. It is a careful practice
to keep the casting studio at a constant temperature to
ensure the quality of a piece.
For more information please visit the
Greenware link on the left.
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