There is an article in the December 2012 "Scientific American" describing a similar occurrence. Apparently a collection of daguerreotypes from GEH began to decay almost as soon as they were placed on exhibit in New York City. The article theorizes a possible cause as well as a strategy to protect them.
I am not involved in this project at GEH. I have talked to the lead investigator many times and some of our work is done in the same labs. I feel uncomfortable about discussing this work any further as it is not mine and I am only peripherally aware of it.
There is no proof that this is an endemic problem to Daguerreotypes, and plenty of anecdotal evidence that there is an external primary contributing factor. Given the age and irreplaceable quality of daguerreotypes, it is better to proceed with caution, but we should not panic a-la Chicken Little and presume this will be the eventual (and proximate) fate of all daguerreotypes. As PE has stated, further research is needed to determine the specific and exact causes along with prevention and remediation methods if possible.Quote:
If the buffered materials are a co-factor in the formation of “white-haze” deterioration it would explain why even with the best intentioned conservation, some plates still changed during exhibition. A questionable environment was enclosed within a stable one.
This remains to be explored and I hope to soon analyze the plate and mat from my example. I present this scenario as a possible alternative and/or co-factor to the silver-chloride scenario presented in the Scientific American article.
I'm still in the process of getting a copy of the article so the answer to my question may already be printed, but were the dags displayed in their orgiinal cases?
I have a collection of Dags, most in their original cases and even those with the seals unbroken there has been increased deterioration. All in dark, cool storage for about 30 years with viewing on rare occasion. Most of what I see appears to be the routine tarnish growth from edges to center... not "white haze", which I've never heard of before this.
The Southworth & Hawes dags were for the most part never in cases originally - they were kept in plate boxes, unmounted, until well into the 20th century. They were then mounted into what was considered to be the most archival preservation materials at the time - buffered mat board, glass and tape. The full details are explained in the links I posted.
Thanks. Will check out those links ASAP.