Treating bronze disease in an ancient Egyptian antiquity

Discussion in 'Ancient Coins' started by DonnaML, Mar 14, 2021.

  1. desertgem

    desertgem Senior Errer Collecktor Supporter

    Thanks, the most interesting thing was the mention of Gamblin conservation colors paints. I didn't know about them , and I often use gamblin oit paints. They have a spectrum and most are under $5, but the amount (ml) isn't mentioned.

    https://conservationcolors.com/videos/

    Jim
     
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  3. dltsrq

    dltsrq Grumpy Old Man

    Following the metaphor of BD as a "disease", I tend to think of successful treatment as remission rather than cure. Humidity is the enemy. If the object were mine, I would probably modify the wooden base to conceal a canister (or packets) of silica desiccant. Nice item!
     
  4. DonnaML

    DonnaML Well-Known Member

    There's an open space underneath the bull's wooden base, between the bottom of it and the floor of the dome. I could simply slide several desiccant packs under there.
     
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  5. romismatist

    romismatist Well-Known Member

    The treatment that the conservator used is legit. Benzotriazole is often used in neutralizing bronze disease; it is used in metal passivation industrially as well (for example, it is used to passivate bronze within industrial cooling towers). The sodium carbonate would is used initially to neutralize the acidic chlorides which create bronze disease.

    Sometimes you may get recurrence of bronze disease even after treatment with benzotriazole, and may require repeat treatment.
     
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  6. DonnaML

    DonnaML Well-Known Member

    One thing I forgot to mention before. If you look at this photo I posted earlier, you'll see that in addition to the uraeus on the sun disk, there's a triangle incised on the Apis bull's forehead. I don't know what it means, but I know it means something, because I've seen it on other Apis bulls. I'll have to do some more research.

    Apis bull new 22 (505x800).jpg
     
  7. Orfew

    Orfew Draco dormiens nunquam titillandus

    Wow Donna that is an awesome artifact. I really enjoyed reading the story of the piece in your posts. I love you photo too. That is an impressive collection of artefacts
     
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  8. DonnaML

    DonnaML Well-Known Member

    I answered my question about the triangle on the bull's forehead pretty easily. See this description of a similar small bronze bull at the Metropolitan Museum of Art:

    https://www.metmuseum.org/art/collection/search/570723

    "Arguably the Apis, unlike many sacred animals in Egypt, was not just favored by a certain deity, but was considered a deity in his own right. A single living representative was stabled near the Ptah temple in Memphis. The bull selected for this important role had certain colorful markings, such as a white triangle on the forehead, and black patches resembling winged birds or scarabs on the body. The bull is often shown, as here, wearing a large sun disc. Similar markings and adornments are easily visible on Apis 17.190.62."

    I noticed that the Met's bull, a "Gift of Darius Ogden Mills, 1904," is not only about the same size as mine, but looks quite a bit like it, except that it's almost entirely covered with a green patina:

    Met Museum Apis Bull R.jpg

    Met Museum Apis bull F.jpg

    Meanwhile, the 1-gram desiccant packs I ordered haven't arrived yet, but the package of small humidity meters I ordered came this morning. The current humidity reading inside the bull's glass dome -- and in my living room generally -- is 30%. It will be interesting to see if the desiccant packs reduce that further, but even without them it's well below the 50% level that people mentioned might raise concerns about the bronze disease recurring.
     
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  9. DonnaML

    DonnaML Well-Known Member

    For the record, after the 1-gram desiccant packs I ordered arrived a couple of days ago, I was able to fit two of them inside the glass dome in the open space underneath the bull's wooden base. After only about 36 hours, there's currently a 6% difference between the humidity inside the dome (23%) and outside on the same shelf (29%). So I guess they're having some effect already, which is promising. At least for now, I'm no longer concerned.
     
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