Plasters and Gypsum Cements

Plasters and Gypsum Cements

Covering the uses and properties of Boral Casting Plaster. Pottery Plaster, Hydrostone, Hydocal 105, White Hydrocal, Ultracal 30 and FGR 95 Alpha Gypsum Cement.

This variety of plasters and gypsum cements are used in mould making, master models and finished art forms. These products originate from the highly versatile raw material gypsum more commonly known as “Plaster of Paris”.

Plaster and gypsum cements

Casting and pottery plasters are manufactured in Australia and are of high quality.  Gypsum cements on the other hand are imported largely from America and the UK.

To give a general distinction between the two commonly used terms, plaster and gypsum cement. Plaster generally refers to a lower strength plaster and gypsum cement is a variety of gypsum plaster that is of a higher quality with special properties.

Gypsum cements generally have a low moisture absorption, high compressive strength and fire resistance. They are more expensive and additional care must be taken in the mixing.  In other words they are harder and stronger than ordinary plaster.


Boral Casting Plaster

This product is used for the economical production of figurines etc. from rubber or plastic moulds. It is ideal for young  children in kindergarten and primary schools as a craft and educational tool. It is widely use in the production of” whiteware”  for use in plaster painting classes.

It is ideally suited for these activities as it has a hard surface that resists chipping and provides an excellent surface for decorating.

Pottery Plaster

This is a high quality white plater with the ability to absorb large amounts of moisture. This makes it ideal for use as a pottery mould by absorbing the water from the pottery slip used in casting. This  leaves a semi- dry reproduction of the shape of sufficient thickness, to enable it to be removed from the mould for subsequent kiln firing, after the excess slip has been poured from the mould.

Gypsum Cements

Hydrostone TB (USG)

Hydrostone is a gypsum cement especially suitable for jobs where high strength and resistance to water absorption are necessary. It is used in high quality novelty art and statuary castings .Chess pieces is a typical, end use.   It works well in latex,  silicone and polyurethane moulds.

White Hydrocal

This is a good general purpose product. It offers slightly better heat resistance together with higher wet and dry strengths. It is ideal for making pottery case moulds.

It is a neutral  gypsum cement with a set time of 25 minutes. It is commonly used for casting both hollow and solid lamp bases and figurines. It is very white in colour.

Hydrocal 105

A good strong mould material. Commonly known as “buff” stone due its colour. It is ideal for casting prosthetics and for dental stones with controlled expansion.

Ultracal 30

This is the most widely 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 foam latex. It has high strength with less tendency to warp. It has a set time of 30 minutes. It has a dry compressive of 6000psi.

FGR 95 Alpha Gypsum Cement

FGR 95 is a unique high strength gypsum cement. It is safe and non-toxic  with zero flame and smoke spread.

Thus is gypsum cement use in the Forton acrylic  polymer modidified plaster formulations.


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One Response to Plasters and Gypsum Cements

  1. Thanks for your comment re our plaster blog. It helps a lot to get comments such as this Regards Stan Alderson

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