Ben's How-To #2
The ABCs of Staining Castings & Models
Typically, there are three types of castings found in a kit: plaster, resin and
metal. Since the manufacturing process of each of these castings is molding, all
three casting types will have some sort of mold release that affects the
staining/coloring process. Although the mold release used in plaster castings
has been absorbed into the gypsum and cannot be removed, the mold release on
resin and metal castings is best removed with vinegar and warm water. Only after
the resin and metal castings have been cleaned and thoroughly dried, can the
staining process begin.
Gypsum - The plaster
(Hydrocal®, LabStone a/k/a Dental Stone, etc.) castings that you receive from a
manufacturer are not all created equal. They range from the weakest and least
expensive (referred to as Plaster of Paris) to the strongest and most expensive
(varying grades of Labstone—mostly used by Dentists and Orthodontists for
impressions and dental repair). Typically, if the castings are white in color
they may be weaker, which is why these castings are usually much thicker. The
white gypsum casting is made thicker so that it will be less likely to break,
especially under extreme conditions such as being knocked over on the workbench
or being thrown around by delivery personnel. Castings made of a stronger
material do not need to be as thick.
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