Mike:
I've had the same experience. The problem, I think, is that the DMG
test is actually TOO sensitive to nickel. All meteoritic metal
is >5% (50,000 ppm) Ni. Metals with only a few hundred ppm Ni will
give a positive result with DMG test, however. I think many steels
and cast irons may have a few hundred ppm Ni.
This subject came up a few years ago on this list and someone (I
forget who) mentioned that in his experience, the swab stayed pink
quite a bit longer with a real meteorite metal while the pink faded
in an hour with "false positives."
Randy Korotev
At 14:09 19-12-08 Friday, you wrote:
Hi List,
If someone has experience with the Allerderm Nickel test and wouldn't
mind sharing their knowledge of how to do it...
I am attempting to do a nickel test at home here and I ran into a bit
of a snag. I have a piece of iron that most likely is not a piece of
meteoritic iron that I was using as a test piece. I sanded a surface
on it, cleaned it with alcohol several times, got out the trusty
Allertest NI test kit from Allerderm, placed a drop each of the
little bottles onto a cotton swab, and placed that on the cleaned
surface of the metal. Using this piece of iron as a control piece, I
wanted to be sure I wasn't doing something in the steps I was using
that would cause me to get a false positive. On this test - test,
the swab turned pink quickly. If I do the exact steps only add in
placing a drop of white vinegar on the cleaned surface, wait a couple
minutes and then apply the nickel test, I get almost a blood red swab
in just the first second. The first time I did this test and saw
this, I thought I had contaminated the surface so I sanded it again
down to a fresh surface, cleaned it several times again with alcohol
before attempting the nickel test without vinegar. Second time, same
result. When using a drop of vinegar again, same result - blood red
quickly.
What am I doing wrong, if anything? Could I still have contamination
on the metal that the sanding and cleaning with alcohol is not removing?
Mike in CO
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