I’ll be conducting some casting experiments this fall. I’ll be looking at shrinking patterning on bronze and aluminum cast eggs. I chose the egg shape for a little more geometric variety than a sphere. We are pouring bronze, aluminum, and differing percentages of the metals to create different patterns. I have two more versions to make; a 75/25 mix heavy in aluminum and one with strategically place aluminum scrap to create specific tearing.
While I am not able to prove anything scientifically, both shrinkage experiments for the bronze went about half way through the egg shape. I don’t know if there is a physics reason for not going through the entire piece.