Re: ATM A 100% Sharpie Test?

[Dan Cassaro <dcass@mediaone.net>]

Nils Olof,
Using my incredible grasp of the very obvious, I just realized this is
already being done every day all around the world.  It's basically a
Magnaflux test.
I worked in a machine shop one summer many years ago, and using a
flourescent penetrating dye (oil based!) and then UV is how they test
parts made in the factory.
Check out http://www.magnaflux.com for the details...
I'll send them an email and see what advice they have to offer, and then
report back to the group.
This might just work....
Dan




Dan Cassaro wrote:

> Nils Olof,
> 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.