Hello Tim, 

It is highly inadvisable to use industrial products on archaeological ceramics.  Because of their relatively high porosity, even with high fired ceramics, the chemicals used are very difficult to removed and can either cause salt fluorescence, staining further down the line, and disintegration of glazes and pigments.  Under no circumstance should acid be applied to a ceramic object as the reaction can be difficult to neutralize and the damage irreversible.  If you are considering de-staining, please contact an archaeological conservator.  The Maryland Archaeological Conservation Laboratory uses a sodium dithionite method, but I wouldn't recommend carrying out this procedure on your own due to the health and safety concerns.  If you would like some additional advice, a quote for service,  or would like to be put in contact with a conservator in your area, please contact me at the number below.  

Regards, 


Nichole Doub
Head Conservator
Maryland Archaeological Conservation Laboratory 
10515 Mackall Road
Saint Leonard, MD 20657
410-586-8577




-----Original Message-----
From: HISTORICAL ARCHAEOLOGY [mailto:[log in to unmask]] On Behalf Of Tim Bennett
Sent: Thursday, September 12, 2013 4:18 PM
To: [log in to unmask]
Subject: Iron Concretion Removal

Hi everyone,

I was wondering if anyone had some tips on removing iron stains/concretions from ceramics.  Last year we discovered a well laden with several cubic feet of cultural material that we've determined was part of a cleanout of the house in April 1910.  Ceramics range from circa 1840s redware to early 20th century porcelain.  Much of the material is in good condition ready for refit/reassembly however some of the fragments have stubborn iron/rust concretions.  I've heard suggestions of using products such as CLR and Whink but was wondering if anyone had some tips or other suggestions as we have quite a bit to deal with.  The assemblage includes a range of materials and decoration such as underglaze transferprints, overglaze decals, white granite (white ironstone), earthenware, stoneware, and porcelain.

Thanks for any suggestions.

Tim Bennett
Warner Site