{"product_id":"u-s-gypsum-duramold-50-lbs-bag-rmduramo","title":"USG Duramold","description":"\u003cdiv class=\"rm-testing-statement\" style=\"border:2px solid #8a5a00;border-radius:6px;padding:12px 16px;margin:16px 0;background:#fdf6e3;\"\u003e\u003cp style=\"margin:0;\"\u003e\u003cstrong\u003eYou must test before you use it, at any scale.\u003c\/strong\u003e Raw materials, mined or man-made, are not consistent. Setting time, strength, expansion and absorption can change from one bag to the next and from one supplier to another, even when the name on the bag stays the same. Before you pour a mold or casting of any size, mix a small test batch with your own water and mixing method, let it set, and check the results.\u003c\/p\u003e\u003c\/div\u003e\n\u003cp\u003e\u003cspan\u003e\u003c\/span\u003e\u003cspan style=\"font-size: 12pt; font-weight: bold;\"\u003eU.S. Gypsum DURAMOLD™ Pottery Plaster 50 lbs. Bag.\u003c\/span\u003e\u003cbr\u003eDURAMOLD was created to meet the demanding needs of the slip casting industry. Compared to #1 POTTERY PLASTER, DURAMOLD features longer mold life and higher wet and dry compressive strength.\u003c\/p\u003e\n\u003cp\u003e– Used at a lower consistency than conventional pottery plasters.\u003cbr\u003e– High wet strength for less breakage in process.\u003cbr\u003e– Ideal for jiggering applications.\u003cbr\u003e– Extended mold life.\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-weight: bold;\"\u003eTechnical Properties \u003c\/span\u003e\u003cspan style=\"font-weight: bold;\"\u003eEnglish Metric\u003c\/span\u003e\u003cbr\u003eUse Consistency (parts of water by weight per 100 parts plaster ) 62 62\u003cbr\u003e1 Hr. Compressive Strength 1,300 psi 8.8 MN\/m2\u003cbr\u003eDry Compressive Strength 2,900 psi 19.7 MN\/m2\u003cbr\u003eTotal Absorption Capacity 30% 30%\u003cbr\u003eMaximum Setting Expansion 0.220% 0.220%\u003cbr\u003eDensity Wet 102.5 lb\/ft3 1.64 g\/cm3\u003cbr\u003eDry 75.0 lb\/ft3 1.20 g\/cm3\u003cbr\u003eSet Time (Machine Mix)* 14-24 min. 14-24 min.\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-weight: bold;\"\u003eGeneral Directions and Guidelines\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-weight: bold;\"\u003ePreparing the Mix\u003c\/span\u003e\u003cbr\u003eUse potable water at temperatures between 70° and 100° F (21° and 38° C). Since variations in slurry (the 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. The higher the temperature of the water, the shorter the set time.\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-weight: bold;\"\u003eSoaking\u003c\/span\u003e \u003cbr\u003eSift or strew the plaster into water slowly and evenly. Do not drop handfuls of plaster directly into the water. Allow soaking for\u003cbr\u003e1-2 minutes. The plaster should be fully dispersed in the water prior to mixing. Small batches require less soaking than large\u003cbr\u003ebatches. See bulletin IG503 for specific soaking instructions.\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-weight: bold;\"\u003eMixing \u003c\/span\u003e\u003cbr\u003eMixing the plaster slurry is one of the most important steps in producing plaster molds with maximum strength, absorption,\u003cbr\u003ehardness, and other important properties.\u003cbr\u003eMechanically mixed plasters develop uniform molds with optimal strengths. Plasters can be mechanically mixed through\u003cbr\u003eboth batch and continuous processes. Proper blade and bucket dimensions are important for obtaining the best batch mix\u003cbr\u003e(see IG503 for details).\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-weight: bold;\"\u003ePouring \u003c\/span\u003e\u003cbr\u003eTo prevent air entrainment and provide a uniform, smooth surface, careful pouring of the plaster slurry is necessary. Agitation of the filled case mold is a further step used to prevent air at or near the mold surface. Whenever possible, the plaster slurry\u003cbr\u003eshould be poured carefully in the deepest area so the slurry flows evenly across the surface of the case mold.\u003cbr\u003ePouring a large amount of slurry directly on the face of the case mold may result in slight densification of the plaster mold\u003cbr\u003eat the point where it strikes the surface of the case. This produces a hard spot, giving uneven absorption.\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-weight: bold;\"\u003eDrying\u003c\/span\u003e \u003cbr\u003eAll pottery molds should be dried as quickly as is safely possible after manufacture so that maximum physical properties can\u003cbr\u003edevelop. Dry to a constant weight.\u003cbr\u003eThe best drying rooms or ovens provide (1) uniform and rapid circulation (minimum of 15-30 fps) of air with no “dead spots”\u003cbr\u003ehaving little or no air movement, (2) equal temperatures throughout the entire area, and (3) provisions for exhausting a portion\u003cbr\u003eof the air while replacing it with fresh air. High humidity surrounding the drying room or oven inhibits the efficiency of the drying\u003cbr\u003ebecause the air pulled into the room is incapable of picking up much moisture from the molds.\u003cbr\u003eThe maximum temperature at which plaster molds are safe from calcination is 120° F (49° C). With substantial free water in\u003cbr\u003ethe mold, higher drying temperatures can be used without difficulty. As drying progresses, the temperature must be reduced to\u003cbr\u003eprevent calcination. The safe drying zone is in the shaded area of graph (below, right). Before removing molds from the dryer,\u003cbr\u003ethe temperature should approach that of the area around the dryer to prevent thermal shock.\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-weight: bold;\"\u003eStorage\u003c\/span\u003e\u003cbr\u003eKeep in a dry, stable environment indoors. Do not stack more than 2 pallets high. Keep from drafts. Rotate stock.\u003cbr\u003e\u003c\/p\u003e","brand":"USG","offers":[{"title":"50 Pounds","offer_id":45113708314946,"sku":"RMDURAMO","price":34.5,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0677\/5508\/2050\/files\/RMDURAMO-2_18c0f106-c4bd-4742-91f0-1b176b88c36c.jpg?v=1791876656","url":"https:\/\/www.sheffield-pottery.live\/products\/u-s-gypsum-duramold-50-lbs-bag-rmduramo","provider":"Sheffield Pottery Inc.","version":"1.0","type":"link"}