Quote Originally Posted by Nodda Duma View Post
You’d have to ask them.

Btw borosilicate isn’t the same as Pyrex. Pyrex is just one form (Corning’s version, to be absolutely correct) of several different makeups. Sort of like there are many different 100 speed B&W films.
From Wikipedia:

“
Open main menu
Wikipedia
EditWatch this pageRead in another language
Borosilicate glass

Guitar slide made of borosilicate glass
Borosilicate glass is a type of glass with silica and boron trioxide as the main glass-forming constituents. Borosilicate glasses are known for having very low coefficients of thermal expansion (~3 × 10−6 K−1 at 20 °C), making them resistant to thermal shock, more so than any other common glass. Such glass is less subject to thermal stress and is commonly used for the construction of reagent bottles. Borosilicate glass is sold under such trade names as Borcam, Borosil, DURAN, Suprax, Simax, BSA 60, BSC 51 (By NIPRO), Heatex, Endural, Schott, Refmex, Kimble, MG(India) and some (but not all) items sold under the trade name Pyrex.

Contents
History Edit

Borosilicate glass was first developed by the German glassmaker Otto Schott in the late 19th century. Otto Schott was also the founder of today's Schott AG, which has sold borosilicate glass later under the brand name DURAN. As part of an equity carve-out in 2005, the DURAN Group was founded and the manufacture of Duran was transferred to it. After Corning Glass Works introduced Pyrex in 1915, the name became a synonym for borosilicate glass in the English-speaking world. However, borosilicate glass is the name of a glass family with various members tailored to completely different purposes. Most common today is borosilicate 3.3 glass such as Duran, International Cookware's Pyrex, NIPRO BSA 60, and BSC 51.

The European manufacturer of Pyrex, International Cookware, still uses borosilicate glass in its Pyrex glass kitchen products,[1] but the U.S. manufacturer of Pyrex kitchenware now uses tempered soda-lime glass.[2] Thus Pyrex can refer to either soda-lime glass or borosilicate glass when discussing kitchen glassware, while Pyrex, Bomex, Duran, TGI and Simax all refer to borosilicate glass when discussing laboratory glassware. The real difference is the trademark and the company that owns the Pyrex name. The original Corning ware made of borosilicate glass was trademarked in capital letters (PYREX). When the kitchenware division was sold, the trademark was changed to lowercase (pyrex) and switched to low thermal-expansion soda-lime glass. The scientific division of Pyrex has always used borosilicate glass[3].[citation needed]

In addition to quartz, sodium carbonate, and aluminium oxide traditionally used in glassmaking, boron is used in the manufacture of borosilicate glass. The composition of low-expansion borosilicate glass, such as those laboratory glasses mentioned above, is approximately 80% silica, 13% boric oxide, 4% sodium oxide and 2–3% aluminium oxide. Though more difficult to make than traditional glass due to the high melting temperature required, it is economical to produce. Its superior durability, chemical and heat resistance finds use in chemical laboratory equipment, cookware, lighting, and in certain kinds of windows.”

How does the extra cost benefit a ground glass focusing screen?