I've had slight to moderate finning - caused by shell damage due to resin expansion - in some castings recently. My B9 models were printed in Cherry resin. This is not usually a problem with my process but it has been - some pretty nasty finning - for the past coupe of weeks.
I cast platinum in Talladium Galaxy 2 investment. This is the hardest / toughest investment I know of.
My last platinum flask had two of the same models in it. My daughter's wedding band. One was vented with ~1mm wire running from inside top of a lady's ring model to the base of the flask. That one didn't show any shell damage or finning in the cast metal. On the vented model- which didn't show any shell expansion damage, there was pink ash residue showing at the bottom opening of the gate of the ring and also way down at the bottom of the tiny vent.
The other EXACT same model in the same flask was not vented and it showed shell damage / finning on the lower half of the ring model and down into the gate.
What makes no sense at all is that I cast some silver from Cherry models in Satincast 20 Gypsum investment - no added chemicals - boric acid or anything - over this Summer and I had no breakage or finning at all.
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