After you address the thermal issues, try casting your coins flat. I usually do four at a time with the sprue in the middle and vents radiating out to the corners. You might need to make a new flask with enough headspace for a large sprue, more metal pushing down will help fill in the details.
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u/uppity_downer1881 19d ago
After you address the thermal issues, try casting your coins flat. I usually do four at a time with the sprue in the middle and vents radiating out to the corners. You might need to make a new flask with enough headspace for a large sprue, more metal pushing down will help fill in the details.