Hi Bonnie,
Thanks for your question. As your wording and the length of this response indicate, cleaning beyond dusting can be fraught, especially when you have a guess but not definitive knowledge about the surface you're working with. The safest option for this level of intervention is to contact a professional conservator, who will be able to examine and test the object to determine the best method of cleaning.
If you do opt to carry out a cleaning yourself, one resource is the National Park Service's Curatorial Care of Wooden Objects, which offers guidance (pasted below) on the question, "Do furniture and wooden objects require more than thorough dusting?" Please be aware, though, that conservators with wooden object expertise offered several caveats to accompany the guidance, which I will also share below.
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From the NPS:
Periodically these require cleaning to remove oils and grime. Objects in storage may need to be cleaned only every ten years while those on exhibit will require cleaning approximately every three years. More frequent cleaning may be necessary if visitors occasionally touch the pieces.
- Use mineral spirits, such as Stoddard solvent or naptha, on greasy types of soils and hand oils. First test a small inconspicuous area with a cotton swab dipped in mineral spirits. If the finish does not get tacky and no finish comes off on the swab, you may begin careful cleaning with a cotton cloth dampened with mineral spirits. Work in a well ventilated area and wear vinyl gloves. Turn the cloth frequently and wipe the object down with a clean, dry cotton cloth after cleaning. Note: Some 18th century pieces may still have their original wax finish. Consult your regional/SO curator and a conservator before cleaning furniture that you suspect has an original wax finish.
- Use soap like Vulpex®, Ivory®, and Orvus® and water to remove smoke and soot from stable finishes. Follow manufacturer's instructions for dilution. Never use detergent because it will leave a film on the surface. Again, test a small inconspicuous area before cleaning the entire surface. Wring the cloth well before wiping. When finished, wipe the piece again with a cloth dampened in clear water and then again with a dry cloth. Do not moisten a damaged, veneered, or inlayed surface.
Only furniture with a sound finish should be cleaned. (p. 18)
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On making the decision about whether to clean beyond dusting, conservator Andrea Chevalier advised working with a conservator, noting that "There are too many unknowns about the surface...Using any of the products in the NPS guidelines without guidance could be problematic on the unknown surface. Using mineral spirits on the sticky surface may not be as straightforward as they think." Conservator Rachael Perkins Arenstein pointed out, "For some kinds of wood objects e.g. African wood sculptures which had oils or coatings applied as part of ritual or use or for historic furniture where the original finish is prized, cleaning using solvents has the potential for damage or removing part of the object's history. That is why we often encourage people to stick to dry cleaning methods." However, if the surface of the crane is not considered historically significant, Rachael felt that the NPS guidelines could be generally appropriate.
On a more technical level, Rachael clarified that "an oil coating is different from a lacquer. Sometimes there are both. Sometimes just one. I would expect a lacquer/varnish/coating to be a distinct layer on the surface. Oiling the surface might have been done if there was no other coating to give a saturated appearance to the wood. In that case I wouldn't see a problem removing it if it was unattractive as long as it didn't solubilize anything underneath or affect the wood." She also cautioned that, "If the solvent testing as outlined [by NPS] results in blanching or hazing then I would recommend calling a conservator."
As you can see, both the cleaning process itself and the decisions around it are complicated. Although I can't offer a clear-cut answer here, I hope this information will help you decide on the best path forward for your particular situation. Please feel free to write again if you have more questions!
Thank you,
Rebecca
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Rebecca Smyrl
Connecting to Collections Care Monitor
Assistant Conservator for Special Collections
UNC Chapel Hill Libraries
Chapel Hill NC
(919) 962-4250
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Original Message:
Sent: 06-29-2023 10:16
From: Bonnie Seymour
Subject: Cleaning wooden crane model
Hello! I need some advice on dusting a model of an Ancient Greek Crane made of wood.
I first plan to dust it with a soft brush and the hep vac, but I know this will not get all the dust. I think they used an oil based lacquer on the wood which is causing some of the dust to stick. What to you think the best method would be to get the stuck dust off without damaging the coating or wood, or should I even try?
Thanks so much!
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Bonnie Seymour
Registrar and Assistant Curator
The Parthenon
Nashville TN
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