Page 414 - Copper and Bronze in Art: Corrosion, Colorants, Getty Museum Conservation, By David Scott

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2 0 The use of Rochelle salt is surprising, since it was with increasing T A concentration, solution tem­
widely believed that sodium potassium tartrate perature, and length of immersion in the solution
was not only potentially aggressive to cuprite lay­ (Notoya and Poling 1979) . This industrial prac­
ers, but that the residues of the tartrate treatment tice, however, is not applicable to archaeological
solution were capable of causing problems in the material. Conservators have a natural reluctance
long-term stability of an object. In some bronze to place any antiquity in a heated solution, espe­
objects there may be a danger of the reprecipita- cially one containing potentially hazardous com­
tion of copper in solution resulting in patches of pounds, such as benzotriazole, that volatilizes
redeposited copper on the surface, which is also easily. Also, the use of heated solutions would
a potential problem with citric acid and sodium considerably increase any health risks associated
polyphosphate cleaning solutions. with this process.
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21 Mauro Matteini, meeting on the conservation of 34 Gerhardt Eggert, letter to the author, 6 June 999.
Ghiberti's Gates of Paradise, Getty Conservation 35 This was ethanol denatured with methanol and
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Institute, Los Angeles, March 999. pyridine to which a blue dye was added. In the
2 2 R. C. Wolbers, conversation with Getty Conser­ United Kingdom, a pink dye was also used.
vation Institute gel-cleaning project team, Los 36 This was ethanol denatured by the addition of
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Angeles, 6 June 999. methanol and /or isopropanol.
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23 Information on Crane's 985 work is from Nicholas 37 Nitrocellulose continues to be used for adhesive
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Veloz, letter to the author, 4 March 996. purposes, however; the English adhesive known
24 Packs of inert but porous materials such as clay as H M (named for its manufacturer, H. Marcel
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or paper can be used to absorb chemical reagents Guest) has remained very popular.
from the surface of treated objects during cleaning. 38 Carnauba wax is the exudate from the leaves of the
25 In 9 8 9 the Times newspaper of London described Brazilian palm (Copernica prunifera) often added
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the auction at Sotheby's at which the sculpture to other waxes to increase hardness and luster.
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was purchased by the J. Paul Getty Museum 3 9 Arthur Beale, letter to the author, 6 May 998.
with the headline, 1 0 0 Pound Sterling Garden 4 0 An accelerated testing regime involving spraying
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Ornament Fetches .82 Million Pounds Sterling the coupons with simulated aqueous media, typi­
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in Sale." cally using salt water.
2 6 Richard Stone, conversation with the author, New 41 An emulsion form of Incralac is now available in a
York City, 8 April 990. water-based system that avoids the use of organic
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27 Arkon p-90 is a product of Arakawa Chemical solvents, but once the curing of the polymer has
Industries, Osaka, Japan, distributed in the United begun it is apparently not readily removed.
States by Arakawa Chemical (USA) Inc., Chicago.
2 8 Shellsol 71, Odorless Mineral Spirits, Petroleum
Naphtha is distributed by Inland Leidy, Balti­
more, Md.
2 9 Laropal aldehyde resin is distributed by B A S F
Corporation.
3 0 B T A is used on copper for industrial applications,
and it has found some use as an effective vapor-
phase inhibitor. For example, paper packing
and storage materials are impregnated with
0 . 5 - 2 % B T A by weight of paper, but because
B T A vapors are hazardous, this application can­
not be recommended for museum use.
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31 Helen Ganiaris, letter to the author, 2 Sep­
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tember 997.
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32 Sue Stock, letter to the author, 0 February 999.
33 For general industrial applications, such as the
treatment of copper roofing panels, the copper
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objects are immersed in a T A solution in water
at a concentration of 0 . 1 - 0 . 5 % (w/v) with a
2 - 6 minute contact time at 0 °C. It is generally
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recognized that the degree of protection increases
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