PLASTER

PLASTER MIXING ROOM (#171)

The Plaster Room is a joint room between Sculpture and Ceramics. Never leave anything in the Plaster Room and always clean thoroughly after use.

Safety Precautions:

Always wear an OSHA approved dust mask when working with plaster.

Never rinse your hands or containers covered with plaster in the sink. Always have a separate bucket of clean water to rinse in. Throw all pieces of plaster in dumpster outside. Plaster will permanently clog drain pipes requiring complete replacement at great expense.

Do not recycle any clay that has been in the Plaster Room. Throw it in the dumpster outside.

IMPORTANT! If you have never mixed plaster, please contact your instructor or the Graduate Assistant.

Mixing Procedure:

1. Fill a bucket with luke‑warm water. The amount of water used should be slightly less than the amount of plaster you think you need.

2. Slowly add plaster by sifting it between your hands into the middle of the bucket of water.

3. Continue to sift until a mound appears and the plaster no longer sinks.

4. Let sit for 2‑3 minutes. Stir with your arm or the mixing drill.

5. The plaster is ready for use when you can draw a line on the surface and it stays briefly.

6. Pour into your mold or whatever your desired use.

7. Clean all containers and room thoroughly.

APPENDIX: DETERMINING AMOUNT OF PLASTER NEED D FOR VOLUME

REQUIRED

One quart of water plus 2 Ibs. 12oz. of plaster makes approximately 80 cubic inches of mixed plaster. Thus: cubic inches =number of quarts required 80

To determine the volume of a form to be filled with plaster, use the following formulas:

For rectangular volumes, V = L x W x H For cylindrical volumes, V ‑ pi x R x R x H (V=volume; L=length; W=width; H=height; pi=3.14; R‑radius)

Use inches as your units of measurement. Your volume will read in cubic inches.

It is a good idea to mix at least a 10% to 20% excess to allow for spills, leaks, and residue remaining in bucket.

APPENDIX: WATER TO PLASTER TABLES AT A CONSISTENCY OF 73

The following table of various volumes of water and corresponding plaster weights, is based on plaster which work well as slip casting molds at a consistency of 73, esogcially U.S.G.No.t Pottery Plaster. Use recommended soaking and mixing times, and 70 F water for best results. (Mixing quantities smaller than 2 quarts is not recommended.)

Water    Pies

1/2 pint                 11 oz.           (or 312 grams)

1 pint '                  1 b. 6oz.               (or 624 grams)

1 quart                 2 b. 120z.               (or 1,248 grams)

1 1/2 quarts                  4 b. 2 oz. (or 1,872 grams)

2 quarts                5 b. 8 oz.               (or 2,497 grams)

21/2 quarts                  6 b.14 oz. (or 3,021 grams)

3 quarts                8 b. 4 oz.               (or 3,74.4 grams)

31/2 quarts                  9 b.10 oz. (or 4,388 grants)

1 gallon                11 b.               (or 4,992 grams)

1 1/2 galbn                    16 b. 8 oz. (or 7,488 grams)

2 galbns                              22 Ib.               (or 9,984 grams)

2 1/2 gallons               27 b. 8 oz. (or 12,480 grams)

3 gallons               33 lb.              (or 14,976 grams)