Close up Pictures of Stir Bars (with a Wide Angle Lens!)

A while ago, we had an offer from ASPEX, a microanalysis company, to provide a free SEM scan of an object of our choosing (that post being a follow up to our M&M mystery post).  The stir bar won and was sent away, never to return.

The results are in, and they are as cool as expected.  Analyst Ben Abraham captured several images of our very, very old stir bar, with corresponding chemical composition analysis.  The stir bar contains several elements, some expected, some not.  At various sampling points around the stir bar, carbon, oxygen, aluminum, silicon, iron, sodium, magnesium, sulfur, chlorine, calcium, zinc, fluorine, and chromium (!)  were identified.  Clearly, after several good years of wear and tear, the surface of the stir bar becomes irregular and several impurities remain on the stir bar.

As a follow up, it would be interesting to see what a brand new stir bar looks like.  Also, it would be interesting to see what two old stir bars look like after a lifetime of cleaning by only soap and water, versus one cleaned regularly with aqua regia or piranha mix or some such cleaning solution.  I don’t know how this analyzed stir bar was cleaned.  Most likely soap and water.

Make sure you click over to the ASPEX site to see the rest of the images and results.  You can also check out the rest of the site, including their desktop SEM.

PS, if you don’t get the joke in the title, watch this.



  1. It would be sad if some poor graduate student’s reaction didn’t work because his new stir bar didn’t have chromium embedded in it due to years of use.

  2. I’m going to send in my disposable contact lens.

  3. Nice. Let us know what happens 🙂

  4. This is sooo cool. I wonder if this wrinkly chromium chunk was. Love the SP reference, too!

  5. *wonder WHAT this Cr chunk was.

  6. Pingback: DIYbio » Blog Archive » Free electron microscopy

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