I bought two Pyrex bowls and went to a glass blower to get them modified. The first one shattered and the glass blower then looked at both of them under polarized light: they both showed strong signs of internal stress. The glass blower was really angry and accused the producer of cheating, because the color was also a slight green, which meant iron was in there, which should not be the case.
According to the glass blower in the professional line Pyrex seems to be worth something, but for normal customer? Not really.
Pyrex is fraud!
I bought two Pyrex bowls and went to a glass blower to get them modified. The first one shattered and the glass blower then looked at both of them under polarized light: they both showed strong signs of internal stress. The glass blower was really angry and accused the producer of cheating, because the color was also a slight green, which meant iron was in there, which should not be the case. According to the glass blower in the professional line Pyrex seems to be worth something, but for normal customer? Not really.
There’s a cool thing where pyrex, Pyrex, and PYREX are all different kinds of glass, age only one of them is the really good scientific-grade glass.
Oh, that might explain it then. Strange that the glass blower didn’t know that.
Only PYREX is the original borosilicate glass. The other two are made with soda lime glass by a different manufacturer.