Re: [ATM] Fused Quartz Blank

[Dominic-Luc Webb <dlwebb@canit.se>]

Glass cannot be manufactured to the precise tolerances, as say,
many plastics, so there will be variations between batches, even
for the same manufacturer. I could envision these Moh's
numbers varying by as much as 0.5, but not much more, and that
was my point. The difference in hardness between plate glass and
borosilicate turns out to be rather small. As regards specifically
Pyrex, I am told by a few sources that Corning has ceased
production, so properties of other borosilcates, such as the one
I listed here from another source, will be increasingly more
relevant for these types of discussions.

I added steel nails here mainly just to be cute. Nails can be
had a lot easier and cheaper than Pyrex, and I happened to know
the Moh's number off the top of my head. Yes, nails work!

Dominic

On Thu, 4 Oct 2007, Guy Brandenburg wrote:

> Seems to me that plate glass is softer than pyrex. What gives here?
> Is it that different sources measure things differently?

>> Quartz: 7
>> "fused quartz": 5.5-6.5
>> borosilicate (Pyrex?): 5.0
>> plate glass: 5.5
>> steel nail: 5.5
>>
>> Dominic

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