Pyrex has been around since 1915. It was developed by Corning, but was spun off, along with Corelleware, into a separate company in the early 1990s. This company is now called Corelle Brands.
Corelle Brands is still an American company, based in Rosemont, Illinois. The European, Russian, Middle Eastern and African divisions of the company have undergone some changes since, but not what we have here. They merged with Instant Brands, the ones that maker Instant Pots, early in 2019.
In the early 1970s, my Gramma came home with new Corelle dishes. This was when they only came in white. She told Grampa they were impossible to break, so he threw them down the basement stairs. Really. And they didn’t break. I’ve heard of them breaking, but I’ve never actually seen it.
Corelle Brands
Corelle Brands makes a lot of other things you have heard of:
- Corelle
- Corningware
- Pyrex
- Visions
- Baker’s Secret
- Chicago Cutlery
- EKCO
- Magnalite
- OLFA
- Revere
- Snapware
- Instant Pot
I am surprised they are all made by the same company. Some sell products made by materials Corning or Corelle Brands invented. Others are companies they purchased.
What are they made out of?
Baker’s Secret: Cold Rolled Steel
Chicago Cutlery: High-carbon stainless steel with synthetic polymer, brushed stainless steel or walnut wood handles
Corelle: Vitrelle, tempered glass consisting of two types of glass laminated into three layers
A glass lamination process thermally bonds two clear “skin” layers of glass to a white or beige “core” layer
Thicker pieces like mugs are made of stonewareCorningWare: Pyroceram ceramic-glass with Pyrex lids
CorningWare Stoneware: Stoneware bakeware with Pyrex lids
CorningWare StoveTop: Pyroceram ceramic-glass with Pyrex lids
Ekco Kitchen Utensils: Stainless Steel and Nylon, Bamboo
Festiva: Glass dinnerware made of transparent soda lime glass
Magnalite Classic: Anodized aluminum shaped in various thicknesses, extra thick at the bottom to absorb and retain heat
Magnalite Professional Cookware: 18/10 stainless steel bodies with a bottom sandwich of 2mm thick copper
OLFA: Craft blades like the 9mm to 25mm snap-off blades, scissors and rotary cutters
Pyrex: Before 1980/1985 thermally resistant clear borosilicate glass
After 1980/1985 soda-lime glass
Plastic lids are availableRevere: 18/6 stainless steel cookware, aluminum is used for cookware with nonstick coating cookware, tin-coated steel bakeware. Revere Copper Clad cookware has copper dipped bottoms.
Snapware: Pyrex with plastic lids or all plastic
Visions: Calexium, transparent Pyroceram ceramic-glass with Pyrex lids
Pyroceram ceramic-glass
Pyroceram ceramic-glass can be heated up to 850°C. It has incredible high thermal shock resistance, going straight from the freezer to the stove, oven, or even a broiler. It can be used in a microwave oven with frozen food.
It was developed or discovered in 1953. S. Donald Stookey, a researcher at Corning inadvertently heated glass to 900 degrees. The glass turned a milky white color. When he accidentally dropped it, it didn’t shatter.
Pyroceram is a ceramic-glass or glass-ceramic. These are made by controlling the crystallization of glass, giving it the “polycrystalline” properties of both glass and ceramic. It sometimes makes glass less transparent and is usually considered a flaw in glass making.
Smooth top stoves are made with glass-ceramic. Corning Pyroceram ceramic-glass was used in the nosecones of ballistic missiles.
Calexium
Calexium is transparent Pyroceram ceramic-glass. It is a beta-quartz material.It was one of the materials patented by Corning research in the 50s. Beta-quartz is not actually quartz. It is a high temperature polymorph of silica to give it a very hard crystal structure that is like quartz.
The difference between Pyrex borosilicate glass and soda-lime glass
Both are clear glass, not the white Pyroceram ceramic-glass that CorningWare is made from. Borosilicate glass bakeware has a higher thermal shock resistance than tempered soda-lime glass. But it stands up better to being dropped or hit.
To begin with, both borosilicate glass and soda-lime glass stand up to exactly the same pressure before it breaks, but the material Pyrex is made out of now is tempered or strengthened, adding an additional six to seven thousand pounds per square inch of mechanical strength.
So, how do you lose your Pyrex? Which are you more likely to do? Drop it? Or go straight from the freezer to the microwave. Just don’t do that and you are okay. If you want to go from the freezer to heat, use Visions or CorningWare.
Snopes: Does Pyrex Brand Bakeware Shatter?
Corelle Vitrelle
Corelle is made of Vitrelle, tempered glass consisting of two types of glass laminated into three layers
A glass lamination process thermally bonds two clear “skin” layers of glass to a white or beige “core” layer