Attack on refractory clay pots by optical glasses.

Examinations were made of the walls and bottoms of approximately 200 refractory clay pots of lined and unlined types to determine the extent of penetration of optical glasses into refractory material. Examinations made with a petrographic microscope of samples of unused pot bottom indicated the structure of the heat-treated refractory. Similar examinations of selected samples from the bottoms of 62 used pots revealed the manner of attack by corrosive glasses and identified the crystalline and glassy reaction products formed. These reaction products were found at the interface between refractory and glass and within pot bottoms penetrated by glass. The pots were used in the manufacture of barium crown, barium flint, light Clown, borosilicate crown, and several different flint optical glasses.