Re: [ATM] Fused Quartz Blank

[Guy Brandenburg <gfbrandenburg@yahoo.com>]

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

Dominic-Luc Webb <dlwebb@canit.se> wrote: On Wed, 3 Oct 2007 vorblesnak@peak.org wrote:

> I usually build my tools out of concrete with a broken glass surface to
> grind on.  Part of my question had to do with the grinding surface on the
> tool, since the cost of the trade is one f4.5 tool to do the other blank
> with.  I normally use old window glass or flattened marbles.  However if
> the fused quartz is significantly harder, perhaps I should use pyrex on
> the tool.  Or maybe a good hard tile.

Mohs Hardness (from different references):

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

Dominic

_______________________________________________
ATM mailing list http://www.atmlist.net/




Guy Brandenburg, Washington, DC
My home page on astronomy, mathematics, education:
http://home.earthlink.net/~gfbranden/GFB_Home_Page.html
or else 
http://tinyurl.com/r6fh2

=============================
"There are enough stars in the universe that if everybody 
on Earth were charged with naming his or her share, we'd
each get to name a trillion-and-a-half of them."
- wrote Anthony Doerr in Orion magazine, reprinted in
Utne Reader, Sept-Oct 2007, page 91
=============================
_______________________________________________
ATM mailing list http://www.atmlist.net/