Dear Heather,
Thank you for your patience. I have a received a response from one of the C2CC Community Experts, a conservator in metals and archaeological materials.
"It depends on the age of these windows but a typical material for caning stained glass historically is a lead compound. Lead is a blue/gray soft metal that even though heavy is soft enough to hold glass in place and can easily be molded and repaired basically by soldering. The problem is what appears to be the issue in these images. I want to say that I cannot tell for certain just by looking at photos but I would guess that these windows do have a form of lead corrosion emerging in areas in the form of the powdery, white/beige product adhering to areas of the solder. If this is the case, one would want to take full PPE precautions when working with it, including moving it, touching it etc. Use a mask (I would not mess around and use a full solvent mask), goggles, gloves and clothing protection. Wash hands thoroughly after working with lead. Lead powder can easily get on hands, become inhaled and/or ingested and it is a cumulative poison that takes a while to leave the body.
It would be best if a stained glass expert or conservator could come an have a look at these windows but in the mean time, the chemical reaction that continues or worsens this corrosion product can be slowed down by reducing temperature, RH and looking for sources of organic acids which are particularly corrosive to lead. These organic acids may be in the form of decaying plastics, but most commonly the are exuded by hardwoods, especially oak. If I were going to do a quick remediation of this issue I would suit up, work in a still place that could be fully cleaned easily with sheets of plastic beneath that could be carefully rolled up with any waste, and carefully try to remove the powdery corrosion with cocktail sticks, cotton swabs and denatured alcohol. Metal/steel tools are too hard for lead and will scratch it easily and never, never introduce a source of water.
But again, I do think it would be best to consult with a conservator if possible who could come and assess the windows in person. I am trying to help but I am not infallible when confronted only with images.
I have found this link (below) from the Australian government that offers some advice on safe handling of such objects. If I can think of anything else, I will let you know!" http://www.environment.gov.au/protection/chemicals-management/lead/lead-in-stained-glass
I hope this is helpful!
Kind regards,
Nicole
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Nicole Festa
Assistant Collection Manager
New York Public Library
New York NY
(917) 229-9731
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Original Message:
Sent: 10-25-2019 12:10
From: Ariana Makau
Subject: Metal corrosion
Hello Heather,
I am the Health & Safety Chair of the Stained Glass Association of America, as well as being a stained glass conservator with 20+ experience both in museum and studio/onsite settings. These different locations require different treatments, but all should require the safety of those interacting with the objects.
It seems from some of your photos you have corrosion and you are highlighting the putty that seals in the glass. Additionally, I want to make sure you are following the proper precautions for lead safety since the photos depict dust on the blanket. You may also have a panel that has both lead and zinc cames, it's difficult to confirm from the images alone.
Feel free to email me if you'd like to talk about it further.
Your partner in preservation,
-Ariana Makau
Ariana Makau | President & Principal Conservator
AIC Professional Associate | Board Member | Health & Safety Chair of SGAA (Stained Glass Association of America)
*main:+510.995.0477 *direct:+510.821.2742
3246 Ettie St #4, Oakland, CA 94608 | CA Licensed & Bonded Contractor #1010577
instagram: @nzilani_glass | web: www.nzilani.com
Original Message------
Hello all,
We have a stained glass window that may be displaying signs of metal corrosion but I am not entirely sure, I have attached some images of the window. Any input or advice would be appreciated, thank you.
Best regards,
Heather Jackson
Collections Manager
Flint Institute of Arts
1120 E. Kearsley St.
Flint, MI 48503
T. 810.234.1695
F. 810.234.1692