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.