Clear As (Borosilicate versus Soda Lime) Glass

I learn all sorts of odd things via my geeky students and former students. This time it’s what chemical mix goes into glass bakeware. I’d never really thought about it.

This weekend I went to a nearby estate sale where grandma’s house was getting sold. Hardly any books, next to no tools in the garage, mostly little figurines and far too much sewing material, but I figured as long as I was there, I’d comb the place from top to bottom.

After I got past the slightly tempting stack of Ice Capades programs dating back to 1972 (Good God, I’m old enough to remember Jo Jo Starbuck), I checked out the cluttered kitchen. Denied my usual estate sale entertainment of people trying to sell various canned pantry contents with 1990s expiration dates, I noticed a TON of bakeware, all of which was immaculately clean.

And some of it immaculately CHEAP, my favorite. I grabbed four purple-tinted (!) baking dishes – 2 were Pyrex, 2 were Anchor Hocking –  maybe $100-125 retail altogether, for $10. (Also a nice deal on a sweeper broom that I used to FINALLY sweep out my garage, but that’s another story).

The purple tint told me the stuff had to be 20-30 years old, but it’s all immaculate – unlike the stuff I already have, not a baked on greasy spot in the bunch.

And then a former student told me on Facebook that since it’s so old, it must be the old school Pyrex made with borosilicate glass – the same kind of glass used in labs, the kind that can stand extreme heat and not shatter when heated and cooled rapidly. Evidently when Pyrex got sold off in 1998, their new owners switched to soda lime glass (the kind used by Anchor Hocking for 2 of my purchases). Turns out soda lime glass handles oven heat as well, but can break easier when temperatures switch too quickly.

This happened to me once – I took a hot glass pie plate and ran it under water in the sink to clean it, and the difference in temperature shattered the damn thing in my hands.

I’m not sure I’ll really notice the difference the same way I notice the difference between using cheaper stovetop material versus upper end stainless or my beloved All-Clad nonstick, but I found it interesting to consider the chemistry in something I hadn’t given second thought to.

I’m too busy thinking about the purple color. I’m thinking it’ll go great if I remodel the kitchen with some avocado green appliances, bright red countertops and some screamin’ monkey-puke yellow colored cabinetry so the place can look like something out of The Brady Bunch. I’d like to think of Alice cooking a lasagna in one of the baking dishes, though I’d rather think of sharing spaghetti with Marcia Lady & The Tramp style, until I leaned in too quickly and broke her nose.

I knew I should have cooked for Adrienne Barbeau instead.