It’s my understanding that the sand each factory used to make marbles played a part in the quality of the glass. I’m under the impression that Pelt’s sand produced the bubbles because of the difference between the sand used in Ohio and West Virginia. Pelts also seem to have the most kiln debris in their clear base based marbles then the other factories. Was it the quality of the kilns and sand that made certain traits more trace able as an ID ? Or ?