Rare Authentic Vintage / Antique 1920-1924 PYREX / Corning Glassworks CASSEROLE / BAKING DISH ---

Clear Glass With Very Pronounced Yellow Tint. In Excellent Condition!

Measures 6 5/8"x10 1/2"x2 1/8", Numbered 231 on one rim and A-L on the on the other rim

--- Has The Circular Corning Glassworks Monogram.

The early clear glass Pyrex ware backstamp was a simple circle with PYREX in an all-caps serif font

with T.M. REG. above and U.S. PAT. OFF. below.

Pyrex (trademarked as PYREX in caps) is a brand introduced by Corning Inc. in 1915 for a line of clear, low-thermal-expansion borosilicate glass used for laboratory glassware and kitchenware. Borosilicate Glass is Much More Resistant to Thermal Shock. Borosilicate glass has a very low CTE (Coefficient of Thermal Expansion) whereas newer "pyrex" in lower case, soda lime glass has a very high CTE. It's for this reason that all high quality cookware is made from borosilicate glass.