No. 1 Pottery Plaster

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AVAILABLE IN 5, 25, AND 50LB OPTIONS IN THE DROPDOWN USG No. 1 Pottery Plaster is the best material available for sanitaryware and dinnerware casting.USG No. 1 Pottery Plaster is f ormulated for long life and reduced breakage which leads to strongermolds. USG No. 1 Pottery Plaster is available with or without thermal shock additive MIXING INSTRUCTIONS Use potable water at temperatures between 70 °F (21 °C) and 100 °F (38 °C). Because variationsin slurry (USG No. 1 Pottery Plaster and water mixture) temperature produce variations in settime, it is important to keep both the USG No. 1 Pottery Plaster and water in a stable temperatureenvironment prior to use. The higher the temperature of the slurry, the shorter the set time.Conversely, the lower the temperature of the slurry, the longer the set time. Weigh both the USG No. 1 Pottery Plaster and the water prior to use for each mix. The water-to-USG No. 1 Pottery Plaster ratio is critical because it governs the strength and absorptivity ofthe mold. Sift or strew USG No. 1 Pottery Plaster into the water slowly and evenly. Do not drop large amountsof USG No. 1 Pottery Plaster directly into the water as proper soaking of the USG No. 1 PotteryPlaster may not occur. USG No. 1 Pottery Plaster should be fully dispersed in the water prior tomixing. Small batches require less soaking time than large batches. See USG IG503 Plaster MixingProcedures for specific soaking instructions. Mixing USG No. 1 Pottery Plaster slurry is one of the most important steps in producing USGNo. 1 Pottery Plaster molds with maximum strength, absorption, hardness and other importantproperties. Mechanically mixed slurries develop uniform molds with optimal strengths. USG No. 1 PotteryPlaster can be mechanically mixed through both batch and continuous processes. Proper bladeand bucket dimensions are important for obtaining the best batch mix (see USG IG503 PlasterMixing Procedures for details). Longer mixing times result in higher mold strength and shorter set times. POURING To prevent air entrainment and provide a uniform, smooth surface, careful pouring of USG No. 1Pottery Plaster slurry is necessary. Agitation/vibration of the filled mold is a further step used toprevent air at or near the mold surface. Whenever possible, USG No. 1 Pottery Plaster slurry shouldbe poured carefully in the deepest area so that the slurry flows evenly across the surface of thecase mold. Pouring a large amount of slurry directly on the face of the case mold may result in slightdensification of the USG No. 1 Pottery Plaster mold at the point where it strikes the surface of thecase. This produces a hard spot, giving uneven absorption. DRYING All pottery molds should be dried as quickly as is safely possible after manufacture so thatmaximum 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(4.6-9.1 mps)) of air with no “dead spots” having little or no air movement, 2) equal temperaturesthroughout the entire area, and 3) provisions for exhausting a portion of the air while replacingit with fresh air. High humidity surrounding the drying room or oven inhibits drying efficiencybecause the air pulled into the room is incapable of picking up much moisture from the molds. The maximum temperature at which USG No. 1 Pottery Plaster molds are safe from calcination is120 °F (49 °C). With substantial free water in the mold, a higher drying temperature can be usedwithout difficulty. As drying progresses, the temperature must be reduced to prevent calcination.Before removing molds from the dryer, the temperature should approach that of the area aroundthe dryer to prevent thermal shock. See IG502 Drying Plaster Casts for additional information. STORAGE AND USE When properly used, USG No. 1 Pottery Plaster is easy to work with and complies with the federalLabeling of Hazardous Art Materials Act, 12 U.S.C. Section 1277 and ASTM D4236. Keep indoorsat temperatures between 65 °F - 75 °F (18 °C - 24 °C) and 45% - 55% RH. Do not stack more thantwo pallets high. Keep from drafts. Rotate stock. USG No. 1 Pottery Plaster should be used within6 months of the manufacturing date located on the package. Always follow handling and usedirections and safety warnings on the package. SDS Show more