Metalcaster wrote:I think the Glass I got was just Plate glass... could be Borosilicate.
If its borosilicate, it should have a water clear edge.
Blue or green edge is usually a soda glass, like regular window glass.
I have seen bluish Corning glass measuring cups which used to be boro.
If you want to get picky ask for BK7. Its a water clear optical glass from Schott. Its used for all those fancy telescopes we use to look for space aliens.
Barium glass, developed by Iittala, is also water clear, but I've never seen any float plate or optical glass made from it. But you never know.
The more water clear the edge is, the better.