Connecting to Collections Care

Hi all,

I started at my current museum just over 2 years ago and one of the projects I have taken on recently is tracking down artifacts that are/have been unaccounted for for years. In doing so, I discovered that two 1840 Empire mirrors which had been missing since the '90s are currently hanging in staff offices. Yay! The problem is they both contain mercury glass. 

Both mirrors hang above the staff members' desks in close proximity to their head/face. One hangs directly above someone's head and the other is directly across from the person's face when they are at their desk.

As far as I can tell, neither mirror is leaking but I have read that they can still release a mercury vapor into the air. 

Is it safe to leave these hanging in the offices or should I remove them? If I do remove them, what is the best way to store a mirror with mercury glass? I'm already looking into developing a mercury safety plan and acquiring a mercury clean-up kit. 

Any and all advice is greatly appreciated! 

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Megan Brigman
Registrar
Columbia, SC
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Dear Megan,

Thank you for reaching out! Indeed, mercury can vaporize at an ambient temperature, starting at 25°C. It vaporizes slowly at that temperature, and triples at 40°C.

An option would be to store them at a low temperature (18°C) and stable relative humidity, with a retention tank to prevent any leakage. 

Some air measurement could also be performed in the office to control the air quality regarding the exposure limit value. 

Preparing a kit to manage mercury is an excellent idea ! It could contain a mercury sponge (Burkle), nitril gloves, Tyvek type 5/6 suit, and a half mask protecting against mercury vapours. 

I hope this helps,

Kind regards,

Alexandra

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Alexandra Lefebvre
Conservator of metallic and technical heritage
Musée De L'Elysée / Atelier vert-de-gris
Lausanne
Switzerland
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Hello Megan,

Very nice job finding the mirrors. 

First, I would remove the mirrors from the staff office spaces.  If they are accessioned objects they should not be in the offices in the first place and as potential health hazards they should be removed.  Storage will be the big issue you need to address.  I will say that from your image they are in really great shape.  Are you sure they haven't been re-mirrored at some point? 

Second, this link should give you all the information you need to deal with the mirrors, https://conservation-wiki.com/wiki/Tin-Mercury_Amalgam_Mirrors.  

Good luck!

Jerry

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Jerry Foust, Ph.D.
Advisor
Freelance/Private Practice
Washington, DC
United States
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Hi everyone,

I also wanted to point to Connecting to Collections Care webinar from several years ago that might be helpful: https://connectingtocollections.org/care_of_tin_mercury_amalgam_mirrors/. 

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Tiffani Emig
Deputy Director
American Institute for Conservation and Foundation for Advancement in Conservation
Washington DC
temig@culturalheritage.org
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Original Message:
Sent: 07-14-2026 08:42
From: Jerry Foust
Subject: Mercury Mirrors in Offices

Hello Megan,

Very nice job finding the mirrors. 

First, I would remove the mirrors from the staff office spaces.  If they are accessioned objects they should not be in the offices in the first place and as potential health hazards they should be removed.  Storage will be the big issue you need to address.  I will say that from your image they are in really great shape.  Are you sure they haven't been re-mirrored at some point? 

Second, this link should give you all the information you need to deal with the mirrors, https://conservation-wiki.com/wiki/Tin-Mercury_Amalgam_Mirrors.  

Good luck!

Jerry

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Jerry Foust, Ph.D.
Advisor
Freelance/Private Practice
Washington, DC
United States
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An always present danger, but I am wondering about encapsulation, pros-cons, and methods

Craig

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Craig Deller
FAIC
FIIC
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Hi Megan, 

How have you confirmed that these are mercury mirrors? Mirrors are incredibly hard to diagnose through photos, but what I see in the center of your mirror looks more like silver mirroring deterioration than tin-mercury. I'm happy to take a look if you have better images. 

I've done numerous mercury vapor readings on mirrors as well as exposure assessments during handling and mercury cleanup. When they are undisturbed, I've never had an elevated reading of concern around mirrors even when they are missing their backs. However, they do not like change. Once we start to interact with them as conservators and collections workers (moving them, taking them apart, working close) the risk of exposure increases particularly when they start to deteriorate and leak mercury. I would expect to see a condition change if you move them and change their orientation or environmental conditions, such as they may start leaking when they didn't before. The risk of leaving them in place is the potential for exposure to the leaking mercury or if they were to get broken. Agitation of the droplets and/or the amalgam causes significant vapor release. If it's not important that they are there, I'm not sure it's worth the risk. 

I would not recommend sealed enclosures or temperature changes. Mercury vapor builds up to dangerous levels quickly when enclosed, so unless you have a well-ventilated area to unwrap them you will get a significant exposure. The good news is that like with mercury-treated herbaria collections stored in cabinets, the vapor dissipates rather quickly. However, the storage materials remain contaminated and will need to be disposed of as hazardous waste.

I would recommend the type of storge system they are testing at the University of Delaware:

Advances in storing and monitoring mercury-tin amalgam mirrors

https://connectingtocollections.org/wp-content/uploads/2023/06/Advances-in-storing-and-monitoring-mercury-tin-amalgam-mirrors-1.pdf

Mecury spill cleanup and disposal are regulated by the EPA, but you may also have local regulations for cleanup and disposal. 

Kerith

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Kerith Koss Schrager
Head of Conservation
National September 11 Memorial & Museum

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