Oh, I buy the glass from the gallery. I wish they’d give it to me. That stuff is expensive!
I think that the "museum" glass is synonymous with water-white.
Jerry taught me a glass-cleaning method that you can use on regular glass but I wouldn’t use this on coated glass like the water-white.
1. carefully file the corners to round off a smidge (this prevents the tape from getting cut)
2. rinse under warm water
3. scrub with a towel and some Soft-Scrub
4. rinse thoroughly
5. dry one side immediately with a blow dryer (just like a daguerreotype plate). THIS is the side that faces the work.
6. towel-dry the other side
I’ve never cut glass. My gallery does tell me that they HATE cutting glass for me if that helps.
I pay them handsomely for that silica so they better just DEAL with it.
Usually the gallery can get away with some rounded edges or quirks because the frame rabbet hides them. Not so with the d-types!