From: Kartik Patel 
To: atm{at}shore.net
Reply-To: Kartik Patel 


Hello, all,

A cement tool onto which glass tiles have been epoxied is presently being
used to grind a 10" mirror blank for my latest project. The gaps
between the tiles which have been filled with candle wax. After completing
the hogging stage and bringing the tool and mirror into full contact, it
was noticed that the wax, initially greyish-white, was now dark grey to
black in many places. Closer inspection revealed that there were grit
particles embedded in the channels. Not a problem, I thought, and ran the
tip of a soldering rod over the channels to melt the wax. This it did and,
as expected, the grit particles promptly sank to the bottom. The excess wax
scraped off, fresh wax deposited where required, and I moved on to grinding
with 120 mesh SiC. It seems logical that that this procedure would have
immobilized the larger grit from the hogging stage. However, the smaller
particles of 120 grit also have a tendency to get embedded in the wax.
After every few wets, there is a layer of sludge in the channels which
closes the air gap between the tool and the blank, thus making them stick.
This layer is stubborn, and does not go away easily on brushing. I have had
to melt the wax channels again to clear the grit, and while it is not a
problem, I anticipate that this will have to be done often as the grit
reduces in size.
During the process of melting, the heat form the soldering rod creates
turbulence in the narrow channel. This churns the grit, and as it
solidifies again the particles are trapped at different depths, depending
on their sizes.
During grinding, the wax surface is also removed, and if a particle is near
to the surface it may get exposed. At some stage I fear that a large
particle may dissapparate like a monster from out of the deep and create
havoc.
Prudence dictates that the wax should be completely removed and replaced,
to prevent this from happening. Sooner, rather than later. The problem is
to decide when.
What experience have users had with this kind of situation? Advice,
comments and user experience would be highly appreciated.

Sincerely,
Kartik Patel,
Mumbai, India
http://www.geocities.com/letapk

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