Don Berry, giving us an idea of just how obsessed we can be, writes :

>Just in case anyone missed the smiley at the end of  Steve's post, let me
>remind the assembled galoothood that:
> 
>(1) a human hair is ca. 100 microns thick
>(2) there are 1000 nanometers / micron, and 10 Angstroms / nanometer
>(3) an average ATOM has a radius of ca. 1-2 Angstroms
>(4) silicon carbide paper has no such specs for waviness
>(5) a "even" layer of spray-on adhesive is a veritable mountain range
>    on this  scale of smoothness.

I just received some 0.5 micron milar film 'sandpaper' from Lee Valley.
They say it is roughly 9000 grit !  That means each bit of grit is
less than 5000 atoms thick !

Actually, LeeValley seems to be using the Japanese scale.  0.5 micron
equates to 3000 US grit, I believe.

I'm really not that AR about sharpening (I use stones) but I was 
looking through the catalog making sure there wasn't anything else
I needed before ordering a new grinding wheel and their tool rest 
and I just couldn't resist.

Paul    (sorry Don...)

Montreal (Quebec)