Pre-Shelling Checks

It is worthwhile to perform a final check on a few items before beginning the shell building process:

  1. Water-tight Patterns - It is imperative that the pattern assembly be completely sealed to avoid slurry leaking into the pattern during dipping. Slurry that seeps into the pattern will likely result in an inclusion in the casting. The pattern was most likely checked on receipt, but it is worth another leak check after pattern assembly before  proceeding with shelling to make sure it is still sealed. if it does not pass the leak check, it is necessary to find the hole or crack and seal. The resulting hump can be smoothed in finishing. Please refer to the Checking the Holes for Leaks section found in the QuickCast Post Processing Guide for further details.

  2. Vents – It is critical that the pattern include at least one vent to allow steam to enter the pattern during autoclave and to allow airflow during the burnout phase. If vents were not added in the assembly process, add them now.