The Abbey Newsletter

Volume 6, Number 5
Oct 1982


The IIC Conference

The "Washington Congress" of the International Institute for Conservation, September 3-9, took as its theme "Science and Technology in the Service of Conservation," and the papers were, as one might expect, pretty technical, though some of the problems they addressed were familiar ones, e.g. communication between conservators and conservation scientists and how to keep newspapers from turning yellow. The preprints include 38 papers and can be ordered from the IIC, 6 Buckingham Street, London WC2N 6BA. Everything was recorded on tape too, the discussions and question-and-answer periods, as well as the papers. The tapes do not duplicate the preprints exactly because the authors had been encouraged to put the basic facts in the written version, and to concentrate on extra illustrative material and additional detail in their verbal presentation. Cassettes can be ordered from Instant Replay Cassette Services, 760 South 23rd St., Arlington, VA 22202 (703/684-8900). Each cassette is $7.00; the whole conference is $138.00. Even the posters in the two poster sessions were documented with abstracts, available as a handout.

There were about 11 papers that related directly to conservation problems in libraries and archives, though none of them concerned book conservation as such. The paper that seemed to give the most new, ready-to-apply information was "Trouble in Store" by Tim Padfield, David Erhardt and Walter Hopwood. This paper dealt with damage from internal pollution to objects on display in closed containers, and it may be useful to anyone who wants to look into the effect of polyester encapsulation on their documents. The concluding section says, in part,

A leakage rate that gives about one air change a day is about the fastest that is compatible with effective damping of the daily cycle in relative humidity but it is also slow enough to allow chemical damage to objects by internal pollution. Exhibition designers should therefore limit themselves to a short and inevitably constricting list of techniques and materials which are probably safe .... general purpose, wide range, showcase pollutant absorber is developed we recommend, as an acid gas absorber, carbonate-buffered paper, laid in cases but not in contact with objects.... The exposed surface area of absorber must be large.... Finally, keep the temperature down!

There is a list of nine "materials known to release harmful vapors at room temperature," given here in full:

Wood, particularly hardwood, releases organic acids, alcohols, aldehydes, esters and hydrocarbons.

Protein-based glues and wool can release volatile sulfides (refined, photographic quality gelatin is sulfur-free).

Cellulose nitrate releases oxides of nitrogen.

Cellulose diacetate can release acetic acid.

Polyvinyl chloride releases hydrogen chloride.

Polyvinyl alcohol is made by hydrolyzing polyvinyl acetate and may continue to release traces of acetic acid.

Polyvinyl acetate and its copolymers are generally regarded as forming very stable films but it certainly releases acetic acid from jars of emulsion.

Polyurethanes contain volatile additives.

Dyes. Some dyes contain labile sulfur--here Werner's test for tarnishing silver is appropriate (A.E.A. Werner, "Conservation and Display: Environmental Control," Museums Journal, 72 (2): 58-60, 1972).

The authors do not mention degraded leather as a source of Pollution, but they do not claim that their list is complete. There is another list, giving "Materials that are Safer":

Metals
Glass
Ceramics
Inorganic pigments
Polyethylene
Polycarbonates
Acrylic polymers (solutions rather than emulsions)
Polystyrene
Polyester fibers
Cotton
Linen

Vincent Daniels reported on a fairly comprehensive study done at the British Museum Research Laboratory, comparing the effects of five deacidification solutions on 56 water color pigments. Seven pigments were found to be affected by some or all of the agents: logwood extract, logwood lake, carthamine, gamboge, litmus, turmeric and cochineal. The author says, in his conclusion:

On the whole, calcium and barium hydroxides seem to produce the greatest color changes and calcium and magnesium bicarbonates the least.

The majority of paintings will contain no pH-variable pigments and will present no problems. Those that do could be treated with the minimum of deacidifying agent, possible by spray application. Spray deacidification has the disadvantage that none of the soluble impurities is removed. As with many conservation treatments a compromise answer should be found.

Gerhard Banik of Vienna, in a paper entitled "Investigation of the Destructive Action of Copper Pigments on Paper and Consequences for Conservation" that he co-authored with H. Stachelberger and Otto Wächter, concluded in part that absence of moisture and presence of magnesium ions would help keep certain copper pigments from destroying the paper they were on and becoming degraded themselves in the process. Strong light and sulfur dioxide have to be avoided too. An unusual method of stabilization is recommended to isolate the two incompatible materials, cellulose and copper, from each other: re-size the paper with an organic bonding agent, e.g. methyl cellulose 25 or 40, to form an insulation layer between the pigment and the support, and incidentally to strengthen the paper. Magnesium bicarbonate can be easily combined with the MC. If the paper cannot be treated in an aqueous system, Klucel G can be used.

Helen Burgess summarized her paper, "The Use of Gel Permeation Chromatography in investigating the Degradation of Cellulose during Conservation Bleaching," in part as follows:

1. Good quality rag (cotton or linen) fibers of contemporary origin undergo very little degradation during peroxide bleaching.

2. Substantially more degradation may result when an "older" rag fiber (e.g. linen fiber no. 4) is bleached, or a less stable wood pulp sample (e.g. kraft fiber no. 3) is treated.

3. It is not possible to detect significant differences in the effects of the pH 8, 9 or 10 stabilized peroxide on the fibers which were bleached.

The significant difference in the effects of treatment upon "new" and "old" fibers illustrates very clearly the dangers of basing conservation recommendations on experiments carried out on contemporary materials.

The technique she used (GPC) is good for showing the molecular weight distribution of polymers. She used it to measure breakdown of cellulose molecules from bleaching with stabilized hydrogen peroxide at different pHs.

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