Customer Service Expert Tips Consistency Calculator Contact Us Find a distributor Product Index Legal EXPERT TIPS Common Problems 1. Plaster Slurry sets before it is sufficiently soaked and completely mixed. 2. Plaster unusually slow in setting. 3. Lumps ranging in size from pellets to rocks are in plaster before mixing. 4. Finished pieces are soft after drying. 5. Finished pieces have small holes on the surface. 6. Finished piece is rough and feels like sandpaper. 7. Large and/or hairline cracks on finished pieces. 8. Finished pieces appear white and chalky regardless of color of plaster used. If slightly abused, the piece crumbles. 9. White powder appears on the face of the finished piece. After powder is wiped away, the face of the piece is rough or pitted. 10. Black, green or reddish-brown spots of varying size on the surface of finished piece. 11. Trapped air on the surface of the finished pieces. 12. Paint will not stick or blisters and/or peels off of the surface of the finished piece. Can't find your problem? Our technical service representatives will be more than happy to assist you in finding your solution. Please call (800)487-4431 or visit our contact us page to find your local sales representative.   1. Plaster Slurry sets before it is sufficiently soaked and completely mixed. Cause A: Contaminated plaster Cure A: Determine if plaster became contaminated after its removal from bag. First mix plaster from the storage bin in one mix. Then, under identical conditions, use plaster directly from the bag for a second mix. Any lumps of setup plaster in bags or storage bin should be removed. If both mixes set too fast and do not appear contaminated, the plaster may be at fault or either of the two following causes may be present: Cause B: Dirty mixing equipment Cure B: Clean all mixing equipment to remove set plaster or other contamination. Dirty equipment accelerates setting time. Cause C: Impurities in mixing water Cure C: While this problem is extremely rare, if excessive alum, chlorine or sulfur is present in the water, the set could be accelerated. Check plaster by making a mix with distilled water. Plaster should always be mixed with water fit to drink.   2. Plaster unusually slow in setting. Cause: Contamination Cure: Confirm that plaster has not become contaminated by sugar, glue or organic acids. If not contaminated, fault could be improper formulation for setting time by manufacturer. Accelerate set by (1) stirring mixture faster, (2) stirring for a longer period of time, (3) using warm water or plaster to make the mix, or (4) using a combination of these three changes in mixing.   3. Lumps ranging in size from pellets to rocks are in plaster before mixing. Cause A: Plaster has absorbed moisture from the air, or water has been splashed into the bin. Plaster has become wet en route to your plant. Cure A: Equip plaster storage bin with tight-fitting lid and keep it closed. Cause B: Cure B: Bags showing evidence of water should be examined before carrier is relieved of responsibility. Note: Paper bags are usually wrinkled when wet, and lumps have a smooth side next to paper. Carrier inspection should be initiated as the carrier is responsible for this damage. Cause C: Plaster has become wet in storage. Cure C: Store plaster in warm, dry, ventilated place; keep off of damp floors. Cause D: Packing lumps in bags of plaster. Cure D: Do not store plaster in dumps higher than ten bags. Always rotate stocks, using older plaster first. Packing lumps usually are the result of lengthy storage. Never use lumpy plaster.   4. Finished pieces are soft after drying. Cause A: Consistency is too high (mix is too thin). Cure A: Mix plaster at recommended ratio. See mixing instructions for selected product, or select a stronger product. Cause B: Pieces have been "burnt" or calcined in the dryer. Cure B: Regulate temperature of dryer at about 120°F and remove pieces as soon as they are dry. If exposed too long, dry pieces calcine and become chalky on the surface at temperatures in excess of 130°F. See drying section for detailed drying instructions.   5. Finished pieces have small holes on the surface. Cause: Large particles in plaster slurry settle out against the face of the mold. Cure: Mix until plaster "creams." Slurry is then sufficiently thick to prevent settling. See mixing section for detailed mixing and soaking instructions.   6. Finished piece is rough and feels like sandpaper. Cause: Large particles in plaster slurry settle out against the face of the mold. Cure: Mix until plaster "creams." Slurry is then sufficiently thick to prevent settling. See mixing section for detailed mixing and soaking instructions.   7. Large and/or hairline cracks on finished pieces. Cause A: Abusive handling. Cure A: Handle pieces properly. Wet (recently demolded) pieces have about one-half of their ultimate dry strength. Cause B: Thermal shock. Cure B: Do not expose hot pieces to cold air drafts. See drying section for detailed drying instructions. Cause C: Shrinkage cracks. Cure C: Dry at moderate temperatures. Calcination (burning) due to drying at extreme temperatures causes shrinking and cracking. See drying section for detailed drying instructions.   8. Finished pieces appear white and chalky regardless of color of plaster used. If slightly abused, the piece crumbles. Cause: Pieces are calcined (burnt) because of extremely high drying temperatures. Cure: Regulate temperature of dryer at about 120°F and remove pieces as soon as they are dry. If exposed too long, dry pieces calcine and become chalky on the surface at temperatures in excess of 130°F. See drying section for detailed drying instructions.   9. White powder appears on the face of the finished piece. After powder is wiped away, the face of the piece is rough or pitted. Cause: Improper drying. Cure: See drying section for detailed drying instructions.   10. Black, green or reddish-brown spots of varying size on the surface of finished piece. Cause: Improper drying. Cure: See drying section for detailed drying instructions.   11. Trapped air on the surface of the finished pieces. Cause A: Improper soaking and mixing of plaster. Cure A: Use a good plaster. Sift plaster into the water evenly. Do not allow large quantities to fall into the water at one time. Let the plaster soak completely until all particles are wetted. Thoroughly mix with a mechanical mixer having the propeller adjusted so air is not whipped into the mix. Mixer should be high speed (approx. 1,750 rpm). Air entrainment is a widespread problem and should be constantly guarded against. Always add plaster to water, never the reverse. See mixing section for detailed mixing and soaking instructions. Cause B: Trapped air on the surface of the finished pieces due to improper pouring. Cure B: Pour plaster while still fluid. In one continuous stream, pour plaster into the deepest portion of the mold until it is completely full. Agitated mold so trapped air rises and fluid plaster filled all cavities of the mold.   12. Paint will not stick or blisters and/or peels off of the surface of the finished piece. Cause: Improper drying of plaster. Cure: See drying section for detailed drying instructions.