[meteorite-list] RE: Polishing slices?

[Matson, Robert]

Hi Darren,

I would consider 220 grit to still be pretty coarse for the purposes
of sanding chondrites.  I always go to at least 400 and often 800.
For chondrites that are hard enough, you can even go to 1500 (the
coarsest polishing grade).  But sanding also darkens the appearance
of most chondrite surfaces, reducing the contrast between chondrules
and ground mass, so you often have to compromise between surface
smoothness and color contrast.  --Rob

-----Original Message-----
From: meteorite-list-bounces at meteoritecentral.com
[mailto:meteorite-list-bounces at meteoritecentral.com]On Behalf Of Darren
Garrison
Sent: Monday, March 07, 2005 1:58 PM
To: meteorite-list at meteoritecentral.com
Subject: [meteorite-list] Polishing slices?


I'm looking for tips on polishing slices.  I have a few NWA slices from Ebay
that show saw marks,
and have been using various grits of sandpaper to smooth the surface, but
while I get a smooth
surface, it still has a dull, matte appearance to it.  I have grades of
sandpaper from 60 to 220,
start with the smallest grit that will still remove the saw marks, then
grade to finer sandpaper
until I reach the 220, after which I try to polish it further by rubbing it
on sheets of white
paper.  I still don't get a surface that looks as good as the
"professionally" polished ones,
though.  Do I need to go down to a specific grit of sandpaper (I see that
they go way beyond 220) or
some other specialized polishing compound?

Look at this example-- the "after" looks much nicer that the "before", but
I'm thinking that the
"after" could look even more nicer.

http://webpages.charter.net/garrison6328/before_and_after.jpg