[meteorite-list] Water cutting question

[MikeG]

Hi Carl,

You raise some very interesting points that I had not considered.  :)

It has been my understanding, that tap water or non-distilled water
may contain chlorine.  It was also my understanding that chlorine is
very destructive to certain components within meteorites and that the
chlorine atoms would initiate a chain reaction leading to runaway
rusting, oozing, flaking, and lawrencite disease.  Drying a specimen
will remove the water, but chlorine may be left behind, so the damage
will continue even if the specimen is thoroughly dried out in an oven.
 I arrived at this understanding by speaking to several other
collectors and dealers with more experience than I.

When I first started out, I used to cut with the same bottled
"purified" water than I drink.  This purified water is basically city
tap water that has been run through filters and reverse osmosis.  When
using this water, my specimens had rusting issues.  After I switched
to distilled water, the rust problems ceased.  The only change in my
routine was the type of water I use for a saw coolant.

So, my experience tends to reinforce my belief that distilled water is
preferable over tap water for cutting meteorites.  But, I cannot
explain the science behind it, if any.

One thing I do now for sure - do not put distilled water in the
microwave in an attempt to boil it for coffee.  LOL.

Best regards,

MikeG

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On 11/20/12, Carl Agee <agee at unm.edu> wrote:
> I have been following the thread on cutting irons in water. My
> question is, why distilled or purified water rather than tap water? I
> was under the impression that purified water, i.e. ultrapure water, is
> much more corrosive than mineralized water like spring water or tap
> water. In fact, ultrapure water is so corrosive it is often used in
> clean labs as a cleaning medium for surfaces. Also, the pharmaceutical
> industry no longer uses stainless steel tubing for ultrapure water
> because of corrosion -- they use Teflon or polyethylene  instead I
> believe.  Wouldn't pure water be worse on iron oxidation than
> "mineral" water? I can understand using pure water to cut down on
> trace element contamination for geochemical srtudies, especially on
> stones, but I don't see how this helps for keeping irons from rusting.
> Also, while we are at it, what is the best blade for cutting irons?
>
> Thanks,
>
> Carl Agee
> --
> Carl B. Agee
> Director and Curator, Institute of Meteoritics
> Professor, Earth and Planetary Sciences
> MSC03 2050
> University of New Mexico
> Albuquerque NM 87131-1126
>
> Tel: (505) 750-7172
> Fax: (505) 277-3577
> Email: agee at unm.edu
> http://meteorite.unm.edu/people/carl_agee/
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