HISTARCH

The cautions suggested by Emily Williams for the chemical cleaning of 
brass buttons and other objects are well said.  From experience, I 
recommend no chemical cleaning of the two-piece hollow button.  The 
cleaning of residue from the inside of these is virtually 
impossible.  Unfortunately this is also true of electrolysis 
salts.  Very gentle dry brushing with fiber brushes (no metal) is 
about all that is suitable for hollow buttons and crotals.

Rick

Roderick Sprague
625 N Garfield St
Moscow, ID  83843


At 11:24 AM 4/13/2008, Emily Williams wrote:
>While many of the postings mentioned using weak acids to clean the 
>buttons none of them referred to the need for rinsing afterwards.  I 
>would like to underscore the critical need for rinsing after using 
>any acid.  If you don't the acid is likely to remain on the surface 
>and can be activated by moisture in the environment causing long 
>term instability and even eradicating the inscriptions for which you 
>were searching.  I would recommend rinsing for one hour in deionized 
>or distilled water.  If you cannot run the water gently over the 
>piece, make sure to change it several times during the course of the hour.
>
>Typically we avoid chemically cleaning copper alloys.  Chemical 
>cleaning is hard to control.  It can remove important information 
>such as textiles fragments, stitching fragment, metallic washes, 
>organic coatings and enamels that could be present on some 
>buttons.  Additionally, it can affect elemental analysis by 
>preferentially removing some components of an alloy.  My 
>recommendation is that before you chemically clean any copper you 
>examine it under a microscope with both raking light and overhead 
>light.  Often inscriptions can be read in this manner or some 
>judicious and gentle mechanical cleaning can be used to remove large 
>areas of concretion.
>
>Emily Williams
>Conservator of Archaeological Materials
>The Colonial Williamsburg Foundation
>Department of Conservation--BHW
>P.O.Box 1776
>Williamsburg, VA 23187-1776
>Tel: 757-220-7079
>Fax: 757-565-8752