Re: [ATM] tile tool sticking

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

Plaster, dental stone, hydrocal, cement, it's all the same in
this regard.  The stuff is a bit porus and thus will adsorb water
until it is full.
Sealing it will stop the adsorption for a little bit but you have
to remember that you have to get down into the stuff in order to
do a real seal and that usually doesn't happen and you'll end up
with patches where the sealing material gets worn away with the
grinding process.  I'd rather not seal and thus get an even
adsorption of the water over  the whole area rather than deal
with spots of non sealed plaster, etc.  This will show up worst
when you are almost done and on the very fine grits where there
will thus be areas where the water goes through and those dry out
and make for problems.
Most of the tile tools are made and then used immediately and are
often kept wet enough that the problem doesn't really exist for
more than a few moments when you start up the next day.\
I'll note that I sometimes do dseal the top of a tool at the end
of the 3220 grit step just to keep the larger grits in the air
holes from falling out and causing problems with the fine grits.
A quick spray of paint of some kind, cheap three dollar can of
paint is fine for this, and that all gets rubbed away on the next
grit.
Another little note. When you start polishing, don't put the
mirror in a plastic bag unless you know that that plastic bag has
not seen any abrasive material or you may end up getting
scratches on it.  Even a wood box that hasn't been painted on the
inside can carry6 grit around and destroy a good surface.  I know
because I am working on a siz inch refractor at the moment and
had been carrying the lenses aroun in a wood box.  Apparently
grit fell off of the tool and/or the lenses and got jostled up
onto polished surfaces when carrying the box around.  Word to the
wise!  Keep things clean when dealing with polished surfaces.
Bob May
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