Hydrocal® White

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AVAILABLE IN 5, 25, AND 50LB OPTIONS IN THE DROPDOWN USG Hydrocal® Brand White Gypsum Cement is a good multi-purpose product for people lookingto upgrade from a standard plaster pr oduct to one that has a higher degree of hardness andimpact resistance. USG Hydrocal White Gypsum Cement is designed for solid and hollow castingand is ideal for giftware and lamp base applications. USG Hydrocal White Gypsum Cement iscompatible with numerous color pigments. MIXING INSTRUCTIONS Use potable water at temperatures between 70 °F (21 °C) and 100 °F (38 °C). Because variations in slurry (USG Hydrocal White Gypsum Cement and water mixture) temperature produce variations in set time, it is important to keep both the USG Hydrocal White Gypsum Cement and water in a stable temperature environment 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 Hydrocal White Gypsum Cement and the water prior to use for each mix. The water-to-USG Hydrocal White Gypsum Cement ratio is critical because it governs the strength and the density of the final cast. Requires 45 parts water by weight per 100 parts plaster. Sift or strew USG Hydrocal White Gypsum Cement into the water slowly and evenly. Do not droplarge amounts of USG Hydrocal White Gypsum Cement directly into the water as proper soakingof the USG Hydrocal White Gypsum Cement may not occur. USG Hydrocal White Gypsum Cementshould be fully dispersed in the water prior to mixing. Small batches require less soaking time thanlarge batches. See USG IG503 Plaster Mixing Procedures for specific soaking instructions.Mixing USG Hydrocal White Gypsum Cement slurry is one of the most important steps inproducing USG Hydrocal White Gypsum Cement casts with maximum strength, absorption,hardness and other important properties. Mechanically mixed slurries develop uniform casts with optimal strengths. USG Hydrocal WhiteGypsum Cement can be mechanically mixed through both batch and continuous processes. Properblade and bucket dimensions are important for obtaining the best batch mix (see USG IG503Plaster Mixing 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 USGHydrocal White Gypsum Cement slurry is necessary. Agitation of the filled mold is a further stepused to prevent air at or near the mold surface. Whenever possible, USG Hydrocal White GypsumCement slurry should be poured carefully in the deepest area so that the slurry flows evenly acrossthe surface of the case mold. Pouring a large amount of slurry directly on the face of the case mold may result in slightdensification of the USG Hydrocal White Gypsum Cement mold at the point where it strikes thesurface of the case. This produces a hard spot, giving uneven absorption. DRYING All casts should be dried as quickly as is safely possible after manufacture so that maximumphysical 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 Hydrocal White Gypsum Cement molds are safe fromcalcination is 120 °F (49 °C). With substantial free water in the mold, a higher drying temperaturecan be used without difficulty. As drying progresses, the temperature must be reduced to preventcalcination. Before removing molds from the dryer, the temperature should approach that of the areaaround the dryer to prevent thermal shock. See IG502 Drying Plaster Casts for additional information. STORAGE AND USE When properly used, USG Hydrocal White Gypsum Cement is easy to work with and complies withthe federal Labeling of Hazardous Art Materials Act, 12 U.S.C. Section 1277 and ASTM D4236. Keepindoors at temperatures between 65 °F - 75 °F (18 °C - 24 °C) and 45% - 55% RH. Do not stackmore than two pallets high. Keep from drafts. Rotate stock. USG Hydrocal White Gypsum Cementshould be used within 6 months of the manufacturing date located on the package. Always followhandling and use directions and safety warnings on the package. SDS Show more