EDTA as cleaning agent for brass

My name is Michiel Langeveld. I am a metal conservation/restoration
student at the Dutch Institute for Cultural Heritage (ICN,
Amsterdam). I'm currently starting on the research for my final
thesis. Part of my thesis research will focus on the use of EDTA
(ethylenediaminetetra-acetic acid) for cleaning of historical
objects made of copper-zinc alloys (not archaeological). The purpose
of this research will find a save and easy to use EDTA recipe.

Because I could not find any consensus in conservation literature on
pH, EDTA concentration, types of EDTA used and buffer solutions I'm
eager to hear what recipes conservators use when using EDTA for
cleaning copper-zinc alloys. I'm also interested in the arguments
for choosing a specific pH, buffer-solution etc.

Information on recipes using other complexing-agents (e.g. PDTA,
NTA) is also welcome. Most recipes in literature use ammonia based
buffer solutions although the use of ammonia is normally not
recommended for copper-alloys. Can anyone tell me under which
conditions and by which mechanism the negative effects of ammonia on
copper-alloys occurs.

At the end of the research the most suitable EDTA (or maybe another
more suitable complexing agent) solution will be used to make up a
cleaning paste with mild abrasives and detergents to find out if
adding these can improve the cleaning properties of the EDTA
solution without having negative effects on the original material.

All recommendations on this project are very welcome,

Michiel Langeveld
Metal conservation student ICN
Indischestraat 1a-zwart
2022 VN Haarlem
The Netherlands


                                  ***
                  Conservation DistList Instance 14:46
               Distributed: Wednesday, February 21, 2001
                       Message Id: cdl-14-46-017
                                  ***