PimplesPimples present as sharp grains on the casting surface. This defect indicates that the metal managed to slightly penetrate the primary shell coat in some areas.

The causes of this defect are evident in the shell portion of the process. To cure these causes, R&R recommends taking the following actions.









  1. Primary stucco touched or hit the wax due to low viscosity of the primary binder or slurry.
  2. Excess draining is creating too thin of a slurry layer and allowing stucco to touch the wax. When the stucco touches the wax, it typically traps air against the surface; which results in a defect.
  3. The fall height of the stucco is too far from the tree (rainfall or barrel rain sander only).
  4. The stucco is too coarse.
  5. Primary slurry is too thin.
  1. Check on slurry viscosity to ensure it is in normal operating parameters.
  2. Reduce drain times, verify that overdraining is not occurring.
  3. Adjust the position of the tree in the rain sander to reduce the distance from the source.
  4. Use a finer stucco on the initial shell coat.
  5. Increase slurry viscosity.







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