Hi Colyn!
Thanks so much for your inquiry. Normally, I am an advocate for performing basic dusting and housekeeping duties for
stable objects on display. Unfortunately for the tinware, which is
not stable, I cannot in good conscience recommend cyclical brushing and the removal of flaking surfaces in perpetuity - for these tinware pieces will likely continue to corrode and more of the object will continue to be lost/damaged while exhibited in these conditions.
Here's my disclaimer: Assessing condition issues from online pictures alone can result in incomplete information and inaccurate recommendations. However, it appears that the tinware is exhibiting aggressive flaking of surface material: in some photos it appears to be delaminating metal plate, in other photos it looks more like an applied coating or finish (paint, enamel?) is lifting from the surface in entire flaked sections. The underlying ferrous metal (to which the tin is plated) is corroding as well- growing dimensionally and exacerbating the sloughing of surface material. Analytical examination would be necessary to confirm the identity of the unstable surfaces of the separate pieces.
Generally speaking, dust accumulation is bad for all objects but can be particularly nasty to vulnerable metal collections. As we've seen in conservation literature, dust can speed up the chemical processes that lead to the chemical and physical deterioration of museum collections. Dust is hygroscopic, abrasive, acidic, corrosive, unsightly, and serves as a food source for unwanted critters (including biological pests- such as mold). As for most metals, the critical RH may be even
lower in polluted atmospheres. Dust and grime left to accumulate on metal artifacts can hold moisture to the surface and may induce corrosion even where the humidity is not that high.
I understand that these items are not of curatorial significance, but since they have been accessioned into the collection they are under the stewardship and care of the historical house. My recommendation is to either have them conserved or pull them from exhibit and store them in a more environmentally stable space until they can receive conservation. The institution may indeed decide to deaccession them due to insignificant historical/curatorial significance and overall poor condition, but that would be at their discretion.
Ultimately, I recommend that the institution pursue having a Housekeeping Plan or a Collections Assessment for Preservation (CAP) plan done (or have these planning documents updated or revisited).
Collections Assessment for Preservation Program | Institute of Museum and Library Services (imls.gov)These can be very effective tools for long-term preservation planning and can help to implement a more holistic approach for preventive maintenance and conservation of individual objects within the institution's possession.
Sidebar: from a health and safety standpoint, one should exercise caution before dusting off potential corrosion products from metal surfaces. Dusting and cleaning unstable surfaces (or utilizing improper cleaning techniques) can often result in irreversible damage to collection objects. Also, sometimes metal alloys and their associated corrosion products can be misleading. For example, you wouldn't want to accidentally make lead corrosion products or mold thriving on a heavy dust layer airborne while thinking you are merely knocking some corrosion from a surface.
I hope this helps, and I don't mean to scare you! Please let me know if I can provide any more support.
Best,
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Nicole Peters
Conservator
NPS Harpers Ferry Center
Connecting to Collections Care Monitor
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Original Message:
Sent: 10-14-2022 12:39
From: Colyn Hunt
Subject: Flaking Tinware
I have some tinware objects (muffin pans, bundt pans, bowls) that have been displayed in a minimally climate-controlled historic house environment for quite a few years. They are not painted. They have collected dust and the surface is now flaking off, in what looks like black metallic flakes. Any movement of the objects results in excessive flaking. The surface appears to be relatively uncorroded beneath the flaking.
These particular items have no provenance and are not particularly exceptional examples, so would be near to zero on a conservation priority list, and we do have the option of deaccessioning.
My current thinking is that I would like to just go ahead and remove the dust and the flaking--since the items are presumably only deteriorating more underneath the dust--and then put them back on display, since they have already been compromised (rather than replacing them with new objects that will then suffer from the same climate). Otherwise we would likely just deaccession them anyway since they would just continue to deteriorate.
I am curious if anyone has information about this particular type of corrosion, and any advice on how to proceed.
--
Colyn C. Hunt | Collections Care Officer
she/her/hers
Historic Richmond Town
Traditional land and ancestral home of the Munsee Lenape people
441 Clarke Ave | Staten Island, NY 10306
(718) 351 - 1611 Ext. 271
historicrichmondtown.org
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ColynHunt
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