Excessive metal with a worm-like appearance that normally occurs in corners
Indicates metal penetrating weak areas, located on the edges of the shell
Causes of this defect are evident in the shell portion of the process; to cure, R&R recommends taking the following actions:
Poor draining due to high viscosity.
Slurries need to be applied in an even, uniform coat. When the slurry viscosity is too high or the tree is not drained properly, heavy layers of slurry are left behind.
Poor draining practice.
Slurries need to be applied in an even, uniform coat. If slurry viscosity is in range, the draining technique may be leaving heavy layers of slurry behind.
Gelling primary slurry.
Check binder stability and implement a proper slurry control program including a gelation test.