Monday, September 13, 2010

Wax off — mini heat gun





Removing the water-soluble PEG wax turns out to be better done with heat first, then using water for cleanup. While the Carbowax we've been using is indeed water soluble, it's not easily water soluble. If a specimen can't handle extended saturation with water and perhaps some scrubbing with a toothbrush, be aware that the wax doesn't melt away easily with exposure to water. I suggest thinking of the water soluble quality of the wax as lending itself to final cleaning of a thin remnant from the fossil's surface.

The bulk of the wax needs to be removed manually, and I've found heat application to be the best option that's easiest on the specimen. I melt the wax and wipe or wick it away. When I get to a layer of cheesecloth reinforcement, I melt the wax and then lift the cheesecloth away from the bone incrementally. Once nearly all the wax is removed, careful water cleaning then removes residual PEG wax. So your specimen needs to be able to hold up to some water exposure and to heat exposure of a few hundred degrees. I'd be concerned about using heat to remove the wax from partially mineralized recent fossils (not something we deal with in this lab).

I've found a good, inexpensive portable tool that provides controlled heat without live flame. The Micro-Therm Flameless Heat Gun can be found on the web for arount $20 (list price from the Solder-it website is $24.95). It comes with a butane lighter without a flint wheel that serves as a fuel reservoir. The lighter has a refill port and apparently you can use regular lighters in the tool as well.

There's a nozzle attachment that's designed for using the tool with heat shrink tubing. I can attest that it's works well for that job. Fossil prep and electrical repair with the same tool.

3 comments:

  1. Just curious if this gives off any smell or possible contaminates when in use?

    I work with a material that I wish to dry the moisture out of quickly but don't want it contaminated.

    Please let me know!

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  2. Hi Edwin, heating up the Carobowax/PEG doe give off volatiles. There's a slight waxy smell when you melt the wax for application and with the heat gun there's more of that smell. I wouldn't use the wax on a porous specimen or on one that you need to keep free from any comtaminant. If the specimen has any signficant porosity, I apply consolidants like vinac or thin cyanoacrylate to fossils before applying the wax. These penetrate the sample and likely reduce the penetration of liquid wax into the surface of the specimen, but of course that also means contaminating the specimen with the consolidants. In our lab, the fossils we work with are Cretaceous age or older and are highly mineralized. Contamination by the water-soluble wax isn't a big concern but it's certainly a prep process we document for future researchers.

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  3. And since I overlooked that you'd be using the heat as a quick dryer, the torch doesn't give off an odor, but it does heat up by burning butane in a catalytic chamber. I'm sure there would be the usual combustion gases, but I'd also expect that some soot could be emitted. The tool doesn't leave an obvious soot, but an electric heat gun would likely be a better choice if that's practical for your use.

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