Atlas of Casting Defects
Positive
Smooth. Raised droplet or “coffee ring” like appearance where ring may be slightly indented into casting
¼” or less
End of part away from the pour cup. Areas where etch rinse water beads up after pattern cleaning or there is insufficient rinse action on the surface of wax. Often in deep corners but can occur on open surfaces.
N/A
Fisheyes
Monitor the etching operation and inspect wax patterns prior to first dip in pre-wet or primary dip
During pattern cleaning prior to shell building, the etch solution is not completely rinsed off. The etch continues to attack the wax forming rings or drain to the bottom of the pattern
| Area | Possible Cause | Potential Correction |
|---|---|---|
| Shell | Incomplete rinse after pattern etch |
Increase agitation during rinse, keep rinse water clean and/or use multiple rinse tanks. Last rinse water should always be clear to ensure cleanliness. Make sure water temperature is room temperature. |
| Shell | Incorrect etch concentration |
Some etch products require mixing with water prior to use. Verify measurements and test concentration if possible. |