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U.S. Gypsum TUF STONE™ Gypsum Cement 100 lbs. Bag
TUF STONE is designed for solid casting with much higher impact-and chip-resistance. Polymer modified and fibered for much higher resilience.
Please note: 100lb bags must be split and repackaged to be shipped UPS. Please expect an $18.00 Handling charge when ordering 100 lb bags shipped UPS.
— Uniquely formulated with fibers to withstand three times the impact pressure of standard materials.
— Excellent resilience and chip resistance.
— Compatible with numerous color pigments.
— Designed for solid casting.
— Ideal for giftware applications.
Technical Properties English Metric
Use Consistency (parts of water by weight per 100 parts plaster) 32 32
1 Hr. Compressive Strength 4,000 psi 27.6 MN/m2
Dry Compressive Strength 10,000 psi 69.0 MN/m2
Maximum Setting Expansion 0.240% 0.240%
Density Wet 122 lb/ft3 1.95 g/cm3
Dry 112 lb/ft3 1.79 g/cm3
Set Time (Machine Mix)* 25-30 min. 25-30 min.
General Directions and Guidelines
Preparing the Mix
Use potable water at temperatures between 70 and 100 °F (21 and 38 °C). Since variations in slurry (TUF STONE™ Gypsum Cement and water mixture) temperature produce variations in setting time, it is important to keep bothTUF STONE Gypsum Cement and water in a stable temperature environment prior to use. The higher the temperature of the slurry, the shorter the set time.
Measuring
Weigh both TUF STONE Gypsum Cement and water at the recommended use consistency for each mix (see
Technical Properties above). The water-to-TUF STONE Gypsum Cement ratio is critical because it governs all physical
properties of the final cast piece.
Soaking
Sift or strew TUF STONE Gypsum Cement into water slowly and evenly. Do not drop handfuls of TUF STONE Gypsum
Cement directly into the water. Allow soaking for 1-2 minutes. TUF STONE Gypsum Cement should be fully dispersed
in the water prior to mixing. Small batches require less soaking than large batches. See bulletin IG503 for specific
soaking instructions.
Mixing
Properly mixing TUF STONE Gypsum Cement is the most important step to producing casts with maximum strength,
hardness, and other important properties. Unlike other plasters and gypsum cements, TUF STONE Gypsum Cement
cannot be mixed by hand and must be mixed mechanically. Additionally, TUF STONE Gypsum Cement can only be
mixed by a batch process, not by a continuous process mixer. See IG503 for recommendations on proper bucket
size, mixing blades, and mixing speeds which are essential to mixing TUF STONE Gypsum Cement properly via the
mechanical/batch process.
Pouring
To prevent air entrainment and provide a uniform, smooth surface, careful pouring of the slurry is necessary. Agitation of the
filled mold is a further step used to prevent air at or near the surface of the cast piece. Whenever possible, the slurry should be
poured carefully in the deepest area so the slurry flows evenly across the surface of the mold.
Pouring a large amount of slurry directly on the face of the mold may result in slight densification of the cast at the point
where the slurry strikes the surface of the mold.
Drying
All casts should be dried as quickly as is safely possible after manufacture so that maximum physical properties can develop.
Dry to a constant weight.
The best drying rooms or ovens provide (1) uniform and rapid circulation (minimum of 15-30 fps) of air with no “dead spots”
having little or no air movement, (2) equal temperatures throughout the entire area, and (3) provisions for exhausting a portion
of the air while replacing it with fresh air. High humidity surrounding the drying room or oven inhibits the efficiency of the drying
because the air pulled into the room is incapable of picking up much moisture from the cast pieces.
The maximum temperature at which TUF STONE Gypsum Cement casts are safe from calcination is 120 °F (49 °C). With substantial
free water in the cast piece, higher drying temperatures can be used without difficulty. As drying progresses, the temperature
must be reduced to prevent calcination. The safe drying zone is in the shaded area of graph (below, right). Before
removing casts from the dryer, the temperature should approach that of the area around the dryer to prevent thermal shock.
See IG502 for more details on proper drying.
Storage
Keep in a dry, stable environment indoors. Do not stack more than 2 pallets high. Keep from drafts. Rotate stock.
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