Fwd: Re: ATM Beginner's questions

["Matthew L. Brown" <mlbrown@everstrive.com>]

>
>Hi James
>
> > 1) Are the grits and all still good after 25 years?
> > I'm guessing they are, but the pitch probably isn't.
>
>%%Grits last forever - go ahead and use them.

Grits last forever, but Edmund packaged them in containers with steel 
bottoms.  Mine rusted after 30 years.  Go ahead and use the 80 grit (you 
don't care about scratches at that stage), but I'd be wary of anything else 
-- the rust will form large particles that will scratch the surface in 
later grits.  A grit kit is cheap compared to the time you'd 
waste.  www.gotgrit.com or Willman-Bell (804)320-7016 .

In fact, I used my Edmund grits to level out the back of 3 different 
mirrors (for prettiness sake, you don't have to do that), so don't throw it 
away, just don't use it anywhere you care about scratches.

>%%I've got the same pot of pitch I used when I made my first
>6" - back in 1973/1974 and it's still OK. You might want
>to add some turpentine to soften it if it's too brittle.

My 30 year old Edmund pitch was still good but needed about a teaspoon of 
turpentine.  Smelled great (Burgundy pitch).

 >>If I am understanding what I'm
reading, you offset the mirror by close to one half of
the diameter and go back and forth with the center of
the mirror close to the edge of the tool? Is there any
movement sideways or is it straight back and forth?

Straight back and forth is fine.  As you get closer to the desired depth 
(say, at 2/3 depth), start moving the center of the mirror towards the 
center of the tool and add a little sideways motion.  It's a convergence 
thing.  As you go down thru the grits, you want the 2 surfaces to approach 
each other to within the diameter of a grit or so.  Most important is that 
you are a little random on everything -- amount you rotate the mirror, 
amount you step around the barrel, stroke length, etc.  Otherwise you'll 
grind a pattern into the mirror, a common newbie mistake (been there, done 
that).

DO search the archives herein.  There are lots and lots of helpful 
techniques that aren't in any book (like making your pitch lap in the 
microwave or ordinary oven and making plaster tools).

=Matt