- 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. |
| *Other set times may also be available. Call your sales representative for more information. | ||
General Directions and Guidlines
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.
Longer mixing times result in higher cast strength and shorter setting
times. The relationship between mixing time and both compressive strength
and setting time is shown below.
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.
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 Òdead spotsÓ 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.
