Benjamin Dattilo

I should show up. I have only a student presenting on some fishes from the Miocene of southern Nevada (Nevada Test Site). I plan to attend and will have federal regulation issues in my head.

It really is difficult to use the right words to describe a thing. I meant a different idea.

Maybe just leave the positive negative off:

A mold forms from the original, a cast forms against a mold. Steinkerns are definitely molds.

I am not authoritative, but I am picky. With steinkerns there is confusion because internal molds are tricky. A mold is a negative impression of the original formed by contact with the original.  A cast is a positive impression of the original formed by contact with the mold. Negative = cast, positive = mold.  Material or mode of filling does not change this. That is level 1 basics, it can get complex…but, maybe later…

To understand the confusion with steinkerns, consider (for e.g, a statue that an artist makes in clay, molds in plaster, and casts in bronze) that typically a mold is a hollow space and a cast is a solid object. In the case of internal molds, the original is a hollow space and the mold is a solid object. No wonder people get mixed up: a steinkern is a solid object. Negative = mold, positive = cast.