I was just about to reply when I saw Kory Barrett's message.  I would further add that great thought and care should be exercised before any archaeological or ethnographic artifact is cleaned.  You not only need to be crystal clear about why any cleaning is necessary, but also crystal clear about what information may be lost or compromised by such efforts.  If the artifact is in stable condition & it's form recognizable (for identification purposes) why clean it at all?  You could be possibly removing or altering micro-wear/use evidence (i.e., vigorous brushing under tap water),  DNA or Blood evidence, and evidence of organic binding media (i.e., glues) which may survive where a lithic point or spear was attached to a shaft.  

It is increasingly recognized that many artifacts which have been traditionally cleaned in the past have been irreversibly altered and that valuable information (i.e., pollen, organic pseudo-morphs, pigments & applied coatings, non-destructive dating analysis) has been either eradicated or compromised.  Even if an archaeologist or collections manager doesn't have access to these resources they may become more accessible for analysis in the future.


Cheers!
Dave

David Harvey
Associate Conservator,
Metals &  Arms
The Colonial Williamsburg Foundation
P.O. Box 1776
Williamsburg, Virginia  23187-1776  USA
Voice:    757-220-7039
E-Mail:   [log in to unmask]