What you should know about the cast
Gypsum is a white powder composed primarily of gypsum. It can be mixed with water to form a thick slurry that can be poured into molds to reproduce objects or used to make a mold that can reproduce finely detailed models.
A variety of plasters and plaster cements are used in the manufacture of molds, master casts, and finished art forms. These products originate from plaster, a highly versatile raw material, better known as “plaster of Paris”.
Plasters used for the manufacture of moulds:
– Ceramic plaster
-Ultracal
Plasters used for casting:
– Ceramic plaster
– Cast Plaster
– Hydrocal
-Hydrostone
-Garden Cast
-FGR-95
plasters to make molds
ceramic plaster
This is a high-quality white plaster with the ability to absorb large amounts of moisture. This makes it ideal for use as a ceramic mold by absorbing water from the ceramic slip used in casting. This leaves a semi-dry reproduction of the form of sufficient thickness to allow it to be demoulded for subsequent firing in the oven, after the excess slip has been poured from the mould.
ultracal 30
This is the most commonly used gypsum cement with the lowest expansion rate available. It is ideal for casting polyester and epoxy resins, as well as being the industry standard for casting latex foam. It has high strength with less tendency to warp. It has a set time of 30 minutes. It has a dry compression of 6000psi.
cast plasters
cast plaster
This product is used for the economical production of figurines, etc. of rubber or plastic molds. It is ideal for young children in kindergartens and primary schools as a craft and educational tool. It is widely used in the production of “white ware” for use in plaster painting classes.
It is ideal for these activities as it has a hard surface that resists chipping and provides an excellent surface for decorating.
White Hydrocal
This is a good general purpose product. Offers slightly better heat resistance along with increased wet and dry strength. It is ideal for making ceramic moulds.
It is a neutral plaster cement with a setting time of 25 minutes. It is commonly used to cast solid and hollow figurines and lamp bases. It is very white in color.
Hydrocal 105
A good strong mold material. Commonly known as a “buff” stone due to its color. It is ideal for casting prostheses and for dental plasters with controlled expansion.
Hydrostone TB (USG)
Hydrostone is a gypsum cement specially indicated for jobs where great strength and resistance to water absorption is required. It is used in castings for high-quality novelty artwork and statues. Chess pieces are a typical end use. Works well on latex, silicone, and polyurethane molds.
garden cast
This plaster cement can be used outdoors. Sets in 30 minutes and can be mixed with equal amounts of outdoor statuary sand.
Alpha plaster cement FGR 95
FGR 95 is a unique high strength plaster cement. It is safe and non-toxic with zero flame and smoke spread. It is designed for fiberglass reinforcement. It is used for complex interior architectural elements.
This is used in Forton’s acrylic polymer modified plaster formulations.
What is plaster cement?
To give a general distinction between the two commonly used terms, plaster and plaster cement. Gypsum generally refers to a lower strength plaster and plaster cement is a higher quality variety of plaster with special properties.
Gypsum cements generally have low moisture absorption, high compressive strength, and fire resistance. They are more expensive and extra care must be taken in the mix. In other words, they are harder and stronger than ordinary plaster.