I bought 2 vintage PYREX measuring cups with green text from a thrift store, One large 1 liter and a smaller half liter measuring cup.
I read online that if it says PYREX in all caps then it's made from Borosilicate glass and that if it's lowercase pyrex then it's made from tempered soda lime glass.
What's unusual is that the measuring cups have different color tints to them. the larger one has a more bluish tint to the glass and the smaller one is clearer and more green.
On Wikipedia it's saying that the more bluish one is made of soda lime, but how can that be since it was made before 1998 and says PYREX?
Does anyone know what's going on or how I can tell which glass is used in these measuring cups?