See our Basic Materials Page for definitions and more details on these products.

Packaged in buckets.

Molders' Plaster or #1 Pottery Plaster

Tooling plaster used to make absorption molds.

CAT #	Description	Price
MP-10	Molders' Plaster, 10 lb *S*	$12.00
MP-25	Molders' Plaster, 25 lb *S*	$20.00
MP-50	Molders' Plaster, 50 lb *S*	$30.00

UltraCal30

A favorite tooling gypsum used to make molds. Can be used for absorption molds. Favorite for making molds for foam latex.

CAT #	Description	Price
CAL30-10	Ultracal 30, 10 lb *S*	$15.50
CAL30-25	Ultracal 30, 25 lb *S*	$26.50
CAL30-50	Ultracal 30, 50 lb *S*	$37.50

Hydrostone

Casting material that is very strong and very white. Can't be "built up" into walls. 10,000 psi. set time 17-20 minutes.

CAT #	Description	Price
HYD-10	Hydrostone, 10 lb *S*	$15.50
HYD-25	Hydrostone, 25 lb *S*	$26.50
HYD-50	Hydrostone, 50 lb *S*	$37.50

Hydrocal White

Casting material that is also strong and very white. Can be used for dental prosthetic work. 5000 psi. set time 25-35 minutes.

CAT #	Description	Price
HYDW-10	Hydrocal White, 10 lb *S*	$16.50
HYDW-25	Hydrocal White, 25 lb *S*	$23.00
HYDW-50	Hydrocal White, 50 lb *S*	$29.00

Hydrocal 105

Dental stone with a yellow tint. 6000 psi. set time 7-10 minutes.

CAT #	Description	Price
H105-10	Hydrocal 105, 10 lb *S*	$16.50
H105-25	Hydrocal 105, 25 lb *S*	$23.00
H105-50	Hydrocal 105, 50 lb *S*	$29.00

Mixing Ratios for Plaster and Gypsum

Molders' Plaster or No. 1 Pottery Plaster
70 parts water by weight to every 100 parts of product.

UltraCal30
38 parts water by weight to every 100 parts of product.

Hydrostone
32 parts water by weight to every 100 parts of product.

Hydrocal White
45 parts water by weight to every 100 parts of product.

Hydrocal 105
40 to 42 parts water by weight to every 100 parts of product.

Example: Suppose you wish to mix 100 lbs. of Hydrostone. For the factory recommended mix add 32 lbs. of water.

Notes: Generally the less water the stronger the end product will be. Most artists mix by sight, which is often a dryer batch than the factory recommendation. A wet batch takes longer to harden and will not have sharp detail. A dry batch usually will have air bubbles or pockets and may harden too quickly. Don't use soft water. Don't breath the dust from these products. Don't use for body casting directly on the skin. It is normal for these products to get hot during the setting process.

For best results follow the following procedure:
1) Measure out powder and water in advance.
2) Sift powder into the water. You may start with about 3/4 of the water needed and then use the remaining water later to adjust your batch.
3) Stir with a Jiffy Mixer (TM).
4) Don't put a new batch of plaster over a partially hardened mix.

This page originally posted: 02/11/1997
This page last updated: 01/15/2010