Agitation of the filled mold is a further step used to prevent air at or near the surface of the cast piece. Pouring To prevent air entrainment and provide a uniform, smooth surface, careful pouring of the slurry is necessary. Longer mixing times result in higher cast strength and shorter setting times. Proper blade and bucket dimensions are important for obtaining the best batch mix (see IG503 for details). Plasters can be mechanically mixed through both batch and continuous processes. Mechanically mixed plasters develop uniform casts with optimal strengths. Hardness, and other important properties. Mixing Mixing the plaster slurry is one of the most important steps in producing plaster casts with maximum strength, See bulletin IG503 for specific soaking instructions. Small batches require less soaking than large batches. The plaster should be fully dispersed in the water prior to mixing. Do not drop handfuls of plaster directly into the water. Soaking Sift or strew the plaster into water slowly and evenly. The water-to-plaster ratio is critical because it governs the strength Measuring Weigh both the casting plaster and water for each mix. The higher the temperature of the water, the shorter the set time. Since variations in slurry (the casting plaster and water mixture) temperature produce variations in setting time, it is important to keep both the plaster and water in a stable temperature environment prior to use. Preparing the Mix Use potable water at temperatures between 70 and 100 ☏ (21 and 38 ☌). Compressive Strength 1,200 psi 8.27 MN/m2ĭry Compressive Strength 2,400 psi 16.55 MN/m2 Use Consistency (parts of water by weight per 100 parts casting plaster) 65 65ġ Hr. #1 CASTING PLASTER is similar to white art plaster, except mixed at a lower use consistency to increase strength, chip-resistant, and to further minimize paint absorption. Hard working surface with reduced paint absorption. The USG plant at Plaster City is also served by the Union Pacific Railroad (UP) and the Carrizo Gorge Railway (CZRY) which is owned by the San Diego & Arizona Eastern Railway (SDAE).- Industry standard for figurines, plaques and lamp bases. In 1947 the first diesel engine was operated on the line. USG purchased the line from Pacific Portland Cement in 1946. Just two years after completion of the line (1924), the track was sold to the Pacific Portland Cement Company. The total length of the line was 19.63 miles (31.59 km). Commercial operation commenced on October 14, 1922. Surveying commenced in April 1921, grading on Octoand construction was completed on September 15, 1922. The railroad built from the San Diego & Arizona Eastern Railway at Plaster City to the quarry. The line was originally built by the Imperial Gypsum Company Railroad and was owned by the Imperial Valley Gypsum and Oil Corporation. Various sources show the total mileage of the track between 15 and 26 miles (24.1 and 41.8 km). The line hauls gypsum rock from the quarry to the plant. The 3 ft (914 mm) gauge line runs north for 20.5 miles (33 km) from the plant at Plaster City (formerly known as Maria) to the gypsum quarry. USG operates an active narrow gauge railway, the last industrial narrow gauge railway in the United States.
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