Re: ATM #500 sandpaper?

[Brian Nestel <blast@aloha.net>]

"Asaf S.-T." wrote: 
> Well, I started cutting today the lens off the Radio
> Shack Jumbo Plastic "thingie", and it's time to use a
> #500 sandpaper. What the heck does that mean? My
> friend who builds airplanes probably has this
> sandpaper (he has several kinds), but what should I
> ask him for?
The #500 refers to the size of the grit bonded to the paper, the same way
the grinding materials you are going to use to shape your mirror are
sized. The largers sizes (smaller numbers) are determined by a sieve
size of so many holes per unit, eg. 80 hole sieve=#80 abrasive.
They can't find anyone with enough patience to drill 500 little
holes, so finer grit is usually measured in microns #500 grit= 20/40 microns
approx, their sizes tend to vary with a bit of overlap like #600 grit =
15/35 microns. this also depends on the manufacturer

-- 
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Brian   Middle of the Pacific,
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