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This sample has a coating which
has to be removed. Then, the old pattern is sanded down removing
the old etched surface completely. In this case several problems
appear. First the sample hasn't been ground down flat and has
rounded edges. The slice also reveals grinding
marks. These are usually camouflaged by the etch but are
not real features of the specimen. The problem is corrected
before re-etching.
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The specimen is lapped
using different grits of polishing paper to bring out the
natural surface and finally a mirror-like finish that will be
ready to etch after final polishing.
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Here's the specimen with the final
mirror-like finish. Notice the reflection of my catalog
and my hand. In the larger version of this image, you can
actually read the lettering on the catalog...that is, if you can
read backwards! |
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Specimen is etched with
a special combination of solutions to bring out the best
Widmanstatten pattern possible. Different irons often
require variations of precise timing and temperature. What
works well with one iron meteorite might not work with another.
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After etching,
the slice is rinsed with pure water and a neutralizing agent is
applied. The slice is then dried and soaked in a
bath of anhydrous alcohol. This process is repeated several
times to purge any residual moisture from the specimen. It is
then placed in a special drier and dried to rid it of any
possible moisture. A further neutralizing treatment is applied
before the last final steps.
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Here's the finished
slice. Notice how bright and crisp the etches surface now looks.
A light buffing or coating is applied to further enhance the
specimen and provide a layer of protect it. Most specimens when
properly prepared will be rust free for many years if maintained
properly. Often, some difficult specimens require more
treatments or more drastic measures to eliminate a chronic
problem. Again proper storage is always encourage.
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