> Fos sheet glass of normal print sizes ( 5x7 to 16x20 ) the glass is all
> made the same way; by the float process. (Molten glass is floated onto a
> liquid lead/tin "table". The flow rate determines the thickness.)
> Anything that could be considered "optical quality" can only be obtained
> by inspecting out the glass with defects. Blemishes aren't the only
> defects, there are striations, inclusions. And the size and obviousness
> of the defect can be subjective.
>
> John
The quality of the glass can vary between manufacturers. Though they use
the same process, ingredient quality, the age of the machinery, its
maintenance and the skill of the operators can vary the quality of the
glass produced.
Sincerely, Art
Art Chakalis
Columbus, Ohio, USA