How to make a thin section without equipment

[Philipp Poeml]

Hi all,

I have a question here:
I have some terribly radioactive material from the Chernobyl accident. It is a silicate melt that formed from the molten core and structural materials from the building. To do a thin section of this stuff would be absolutely mega cool.

As you can imagine I have to do that in a glove box to protect myself. There is no automatic thin section machine in that glove box. What I do have in the GB is a low speed diamond saw to section the sample.

How can I make a thin section with the least possible equipment? Like, manually, by hand? I think that should be possible. I can introduce certain things into that glovebox (which are contaminated and lost then) so I want to minimize waste, cost, and so on.

Is there a howto out there on how to do this? A good book?

I have never prepared a thin section myself, only polished mounts. So I am familiar with gluing, polishing discs etc, but this would be quite special.

Is it enough to just cut a slice of the material (parallel surfaces) glue it onto a glass slide and then polish it down on polishing paper until it allows light to pass? How would I control the thickness? I have no transmitted light microscope in that box I am afraid. Is there something that I could embed along with the slice that would give me a thickness indication by its color in transmitted light, when checking with a magnifying glass or so?

Thanks for any ideas!

Cheers
Philipp

[John Donovan]

I have some terribly radioactive material from the Chernobyl accident. It is a silicate melt that formed from the molten core and structural materials from the building. To do a thin section of this stuff would be absolutely mega cool.

Very cool... not "hot" at all! 

Seriously, I made hundreds of thin sections by hand at UCB when I was investigating blueschist minerals about 20 years ago.

I used SiC and Al2O3 powders on glass plates with water for the grinding and polishing. The only thing I used a mechanical device for that would have been difficult by hand is the thin section cutoff operation, after the "chip" is glued to the slide, to get it roughly 1 mm thick prior to hand grinding.

I would ask Tim Teague at UC Berkeley- he is an expert at weird sample prep. There's also Rollin Lakis who does a lot of "active" sample prep. I would also contact him:

Rollin E. Lakis
rlakis@lanl.gov
+1 505 665 9814
+1 505 665 7815 FAX
Los Alamos National Laboratory
PO Box 1663 MS E574
Los Alamos, New Mexico 87545

In the meantime here's a good and slightly related "Explain This..." picture:

http://probesoftware.com/smf/index.php?topic=144.msg736#msg736

[Philipp Poeml]

Thanks for the info John! I will follow up on this and contact the people you suggested. So far I have always used SiC paper and diamond spray on polishing cloths. I never worked with these glass plates. Do you know why they are used for thin section preparation?

Thanks again
Philipp

[Probeman]

Thanks for the info John! I will follow up on this and contact the people you suggested. So far I have always used SiC paper and diamond spray on polishing cloths. I never worked with these glass plates. Do you know why they are used for thin section preparation?

The glass plates are just for a flat surface that can be rinsed easily to remove the grinding/polishing material from the previous steps. The key is to use your finger pressure on the back of the glass to increase the grinding action on various areas of the thin section glass (which will bend very, very slightly to allow this) to bring the thickness down evenly over the whole section, given that different hardness materials are often in the same section.

To judge the thickness of the section one would normally use a petrographic microscope, however, this device here which we use, is much easier for all hand thin section grinding because one can see the crossed polarizer view from arms length!

http://www.buehler.com/equipment/petrography/petrographicgeological-equipment/petrovue-thin-section-viewer