Here are several points to consider:
1. The Cl in tap water is of a different for and will not remain in water more than 24 hours at room temperature. Tap water causing BD is an old myth.
2. Generally the sodium carbonate/sodium bi-carbonate mix with not damage copper-carbonate patinas, it will remove the ones containing soft copper-chloride mixed patinas.
3. The use of sodium carbonate/sodium bi-carbonate has been in use for at least 90 years, and was heavily discussed and articles publish as far back as the 1930's.[/font] There is a recent document published by the University of Texas [year 2000], and re-written and modified by me, and is here on
Forum, with references, it has been here for 5 years or so. I would also recommend this article:
JAIC 1994, Volume 33, Number 2, Article 6 (pp. 141 to 152)
A PERSPECTIVE ON THE
HISTORY OF THE CONSERVATION OF ARCHAEOLOGICAL COPPER ALLOYS IN THE
UNITED STATES by TERRY DRAYMAN-WEISSER, this can be found on-line and is worth reading. There are several
other books, recently published that also talk about the carbonate/bi-carbonate method of removing chlorides.
Bruce