Re: ATM A 100% Sharpie Test?

[Dan Cassaro <dcass@mediaone.net>]

Nils Olaf,
That is *brilliant*  (pun intended). I was going to use red Dykem as
John Upton suggested, but pits that fluoresce basically scream "Here I
am!", instead of hiding... Wow.
Let's seem if anyone has a suggestion for the ink, and I'll start
searching on my own...
Dan


Nils Olof Carlin wrote:

> Dan,
>
> >A crazy thought:  could one spray the entire surface of a fine ground
>
> >mirror, thus filling all the pits with ink, let dry, and then grind
> >until *all* the black pits were gone?  It would certainly make
> finding
> >pits much easier...
> >Has anyone tried this?
>
> Not I, half an hour ago. But why wonder, if you could do a pilot
> study? I took two slide glasses, beveled the edges with a stone for
> safety. A few seconds with #150 grit produced some nice test pits, to
> color with a layer of "sharpie" ink. After a wet or two of #400 grit,
> I could see with a magnifier some pits were indeed inked, but not all.
>
> Then the thought struck me - would fluorescent ink be any good, using
> a UV "blacklight"? First try showed my yellow underline pen was
> water-soluble - so I had to do my next #400 "wet" with a drop of salad
> oil instead. With the glass near the UV light, the remaining pits were
> very much more conspicuous this way, so if you could get a water
> resistant fluorescent "sharpie" (I'm sure there must be), the
> sensitivity of the test would likely be very much improved.
>
> And you would know for sure if the large pits are left over from the
> old, coarse grit or are from the new, finer one.
>
> Just a pilot study, any volunteers for a full-scale one? ;-)
>
> Nils Olof
>
> In case you wondered: no UV seems to pass my glasses, at least holding
> them between the light and a paper kills all fluorescence.