- The best available
for sanitaryware and dinnerware casting
- Formulated for
long life and reduced breakage (stronger molds.)
- Available with
or without thermal shock additive.
| Technical Properties | English | Metric |
| Use Consistency (parts of water by weight per 100 parts plaster ) | 74 | 74 |
| 1 Hr. Compressive Strength | 850 psi | 5.8 MN/m2 |
| Dry Compressive Strength | 1,800 psi | 12.2 MN/m2 |
| Total Absorption Capacity | 41% | 41% |
| Maximum Setting Expansion | 0.190% | 0.190% |
| Density | ||
| Wet | 97.6 lb/ft3 | 1.56 g/cm3 |
| Dry | 66.0 lb/ft3 | 1.06 g/cm3 |
| Set Time (Machine Mix)* | 14-24 min. | 14-24 min. |
| *Other set times may also be available. Call your sales representative for more information. Hand mix times will be longer. | ||
General Directions and Guidelines
Weigh both the plaster and water for each mix. The water-to-plaster ratio is critical because it governs both the strength and the absorptive capacity of the mold.
Mixing the plaster
slurry is one of the most important steps in producing plaster molds with
maximum strength, absorption, hardness, and other important properties.
Mechanically
mixed plasters develop uniform molds with optimal strengths. Plasters
can be mechanically mixed through both batch and continuous processes.
Longer mixing times
result in higher mold strength and shorter setting times. The relationship
between mixing time and both compressive strength and setting time is
shown below.
Pouring a large amount of slurry directly on the face of the case mold may result in slight densification of the plaster mold at the point where it strikes the surface of the case. This produces a hard spot, giving uneven absorption.
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 molds.
The maximum temperature at which plaster molds are safe from calcination is 120°F (49°C). With substantial free water in the mold, 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 molds from the dryer, the temperature should approach that of the area around the dryer to prevent thermal shock.
