> Whether Pyrex switched from using borosilicate glass to tempered soda lime glass only after Corning sold the brand to World Kitchen in 1998.
…
> In a January 2011 article on glass bakeware, Consumer Reports stated that they were unable to determine exactly when major U.S. manufacturers (including Pyrex) switched
> What's Undetermined
> Whether Pyrex switched from using borosilicate glass to tempered soda lime glass only after Corning sold the brand to World Kitchen in 1998.
…
> In a January 2011 article on glass bakeware, Consumer Reports stated that they were unable to determine exactly when major U.S. manufacturers (including Pyrex) switched