Data Sheets for Plasters

Data Sheets give mixing, best use, technical, and storage information. Click on the images for a PDF to print. Hydrocal comes in White (USG6) and Yellow (USG12) with the only difference being the color addition, which is not pertinent for the technical information.

USG1 Pottery	USG2 Molding	USG3 Casting	USG4 Dental	USG6 & 12 Hydrocal	USG7 Cerami-Cal	USG11 Hydrostone

Plaster

Plaster is one of the most flexible, versatile art materials made. Molds, sculpture, hobby crafts, medical and dental uses: plaster serves all these needs and more. We can help you determine which plaster is right for your intended application. All plaster is packaged in standard 50-pound bags. Other types of plaster and gypsum stone are available with minimum orders of 2,000-4,000 lbs.

Plaster Mixing Instructions

General Mixing instructions -
Your mixing container and equipment should be clean and free of all previous plaster mixing debris. Old plaster will cause your new mix to set irregularly and at a faster rate.
Water needs to be carefully and specifically measured. Water temperature is very important to your set time. Testing water is at 70°F - use a thermometer! Hotter water will speed up your set time, cooler water will slow and retard the set time.
Plaster mixes into water: sift your plaster into the pre-measured water, allow to slake for 30 seconds and mix time will be about 30 - 60 seconds. Plaster ages, it is hydroscopic. Older plaster may require less water.
Adjusting and checking your Georgia Pacific (GP) plaster against USG plaster:
Nothing will be exactly the same as we all know. Correctly adjusting and controlling your water will be the key to achieving the best match for your needs.
Field Test Procedure - You will need the following:
• Waxed or Plastic cup
• Wooden stir stick
• Thermometer
• Timer
• Straightened paperclip
Mix using 200 gram test amounts with the prescribed water for the given plaster at 70°F. Mix in your cup as directed. Set your timer. As soon as the slurry appreciably stiffens, begin inserting the extended paperclip. When considerable pressure from your index finger is required to reach the bottom of the cup, you will have your set time. Test absorption by allowing the test cup of plaster to set overnight. Weigh your slug of plaster. Cover with room temperature water and soak for an hour. Re-weigh your slug of plaster. The % difference in weight will be your absorption. If you are matching this to your USG version, you need to make a slug of each for control purposes. If your set time or absorptions are different, these will be adjustable with more or less water and the temperature of the water.

For USG1, USG2, USG3, USG4, and USG5:

For USG7:

For USG6 & USG12:

For USG11:

Plaster Gauze Rolls

Plaster Gauze • 50081K For masks, mold backing, foundations and parts of sculptures; there is no end to the hundreds of uses for this versitile tape. Each box contains one roll that is 4" wide by 15' long.

Mold Soap

A soapy separating agent used to release plaster or other materials from plaster. We recommend applying a coat, wiping it off, blotting with a tissue or soft cloth, and then repeating for a second coat. Sold in pints only. RM603 • $11.25 Qty:

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Georgies Ceramic & Clay Co. • 756 NE Lombard • Portland OR 97211
Phone: 503-283-1353 • Fax: 503-283-1387
Store Hours: Monday-Friday 9:00a-5:00p Pacific time • CLOSED Saturday & Sunday