Frank, nice effect with the cooler metal! (Metal metal, that is
) Isn't glass just a fascinating medium? Whoda thunk it would cause a texture like that?
Ivo, those are great explanations, but most of that I know already about pressed and mold-blown glass. I might add that some "turn molds," your second category, are iron as well, but coated with a baked-on cork or sawdust mixture to hold water for the steam - hence their other name, paste molds. The purpose of the steam is to keep the glass from touching the mold, so it remains nice and smooth. This part about press molds I don't get, though: "For making hollow vessels, two moulds are used, and parts assembled." Do you mean two (or more) parts are used? Why would you use two moulds?
As far as I know, Steuben didn't make any pressed glass. So assuming Corning's ID is correct, this was blown. This is supported by the fact that the lower half of the pitcher is fluted, waisted, and of uniform thickness.
Christine, your piece is pressed, and that's why you can't feel any indentations on the inside.
This type of design, with the thicker medallions, seems pretty uncommon. Given Carder's propensity for innovation and experimentation, I think we have to consider the idea that these were made using uncommon techniques.