Re: Solvents -Reply

["Sally Shelton" <Shelton.Sally@NMNH.SI.EDU>]

The FIRST thing you do is to determine the geochemical and biochemical nature 
of both the fossil and the matrix. I get ~40 messages a year from people asking 
which acid to use on "fossils." As there is no one fossil or matrix 
composition, or preservation mode, or problem, there is no one acid or solvent 
to use (NOT the same thing--be very careful here, as this terminology is exact 
and precise, as you'd expect from chemists). 

The SECOND thing you do is to determine what the disadvantages are and what 
information you will use with the use of any chemical cleaning or treatment 
method, and balance the costs and benefits. Scenarios vary. In some cases, the 
morphology is more apparently important than the composition. In other cases, 
there is most value in keeping a chemically pristine sample for delicate bio- 
and geochemical work, and that's becoming more important every year. In still 
other cases, the matrix has more to say scientifically than does the fossil. 

The THIRD thing you do, if you establish that a solvent or acid is called for 
in preparation, is to get yourself over to OSHA or comparable training on the 
use of protective gear and equipment, and on which protective gear and 
equipment this method calls for. You have a right to know this (indded, a 
positive obligation), and such training is supposed to be provided free and on 
demand by employers in the US. 

I am appalled anew every time a case comes to light in which someone heard 
about a chemical prep method and never read up further before deciding to use 
the same. That's voodoo science and has cost the health (and a few lives) of 
people (and destroyed quite a few specimens). I am further appalled anew every 
time I hear about careless lab prep methods being passed on through oral 
history and ancestor worship instead of formal qualified lab training. When you 
have a chance to do it right from the ground up, take it.

Cheers, Sally Shelton
Collections Officer
National Museum of Natural History
Smithsonian Institution