Re: [ATM] Scratches keep forming on edge of mirror

["Bob May" <rmay@nethere.com>]

Paster or stone, it is really all the same as it is waterproof
for degradation of the material when wet.  The stuff isn't called
waterproof only because it does adsorb water.
If you have the tiles sitting on top of the tool, you need to
bevel all of the edges of the tiles.  If they are buried into the
plaster, you only need to bevel ones that stick out from the edge
of the tool.  The plaster supports the tiles embedded in it so
they they don't crack off.
For filling in holes, just sprinkle some amount of the plaster on
the face and mix right there on the tool with some water and
thrash it about with a spatula or putty knife to fill the holes
up.  Don't worry about ridges, etc that come aout from doing this
with the excess plaster as a single wet of grit will clear them
offf of the tool.
Probably7 what is happening on youu case is that the chips that
you have done with the coarse side of the sharpening stone have
made little clamshells in the edge of the glass and you're
kicking them off of the edge as you go along.  What makes it
worse is that everytime you have found these scratches, you went
and reground the edge again, causing more of the clamshells.
Grind with the fine side of the stone and then, if desired, use
some of the fine grit and a piece of iron or stee or even
brass/bronze and grind the angle further.  I find that forty five
degrees is just fine and a thirty second of an inch is wide
enough whn you get to the fine grinding point.  You don't need
much beveled area as it is the angle that keeps the glass from
spalling material off and that angled area doesn't need much
backing to do it's job.  As another poster said, keeping the
bevel to the same or finer grit will help insure that the
clamshells that do break off will not seriously affect the
surfacce of the mirror.
Bob May
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