26 March 2019

Do you have PYREX or pyrex in your kitchen ?

I found both in our cupboard.
Borosilicate PYREX Glass has excellent thermal shock resistance. It does not expand or contract like ordinary Soda-Lime glass does when exposed to rapid changes in heat or cold. Unfortunately when Corning, Inc. sold off the PYREX® trademark it became pyrex® in America and the new company started using Soda-Lime Glass instead of Borosilicate Glass. The company that bought the PYREX® trademark for European use continues to make Borosilicate Glass PYREX.
This 2-minute Consumer Reports video uses extreme conditions to demonstrate the difference:


  1. Good too know! The part where they say that sand gets hotter than food in an oven is pretty inaccurate though.

    1. They've clearly never heard of pizza sauce.

  2. The one one the right will break. You can see how it's got that kind of bluish cast to it, on the edge? That was my clue it was the SL glass. The BS glass more yellow. If you have, say, glass stir rods, you can really see that effect by holding so they act as light pipes. I'll see if I have any in the lab and send a picture, but I think all our new stir rods are the cheap kind.

  3. Sadly, my glass measuring cups are "Anchor Hocking."

  4. This caused a lot of waves in the world of illegal drugs.

  5. I learned this about Pyrex years ago, but did not know about the text difference. It's not about the type of glass they switched too, but more specifically the coefficient of expansion of their new glass. The COE will determine how stable the molecules are at a certain temp and how happy they are with that changing quickly. It's really quite fascinating. I learned about this when I discovered the amazing world of dichroic glass and glass fusing. I need to pull out my kiln and glass again.


Related Posts Plugin for WordPress, Blogger...