LETTERS TO THE EDITOR
1.1 To the Editor:
With reference to the editorial containing comments by Robert E. Fieux (v. 19, no. 2), I would like to express my agreement that conservators should become more aware of “new high-technology materials.” We should, however, be sure that any new materials being considered “in place of archaic traditional ones” be indeed superior in terms of our specialized needs. For example, a new adhesive will not be preferable for art conservation if it reacts harmfully with the materials of the art work or if it cannot potentially be removed in the future. In some instances a traditional material or technique may still be best. Thus an increased interest in high-technology materials must be accompanied by careful research with our requirements in mind.
I can emphatically concur with Mr. Fieux's statements about the difficulties faced by independent conservators involved in developing new techniques. Nor, in my experience, has it been easy to convince art institutions of the need to regularly support this type of research: formal research that will lead to the improved care of countless objects, not just those of immediate concern to the institution.
Therefore I suggest that every institutional member of AIC be required to make an annual contribution for conservation research, either directly within their own conservation departments or through donations to AIC to be conducted by professional members. In addition, AIC should publish the titles and authors of all completed research reports, thereby making them accessible to any member who wishes to write directly to the researchers. In this way AIC can encourage a responsible linking of modern technology with the developing science of art conservation.
Let it not be said about us that “If the only tool you have is a hammer, you tend to see every problem as a nail” (Abraham Maslow).Jean D.Portell13 Garden Place, Brooklyn, NY 11201
1.1 To the Editor:
Upon first receiving a copy of Archeological Chemistry by Zvi Goffer, I had hoped to find the time to review it for a conservation periodical. It was with some interest, then, that I read Eugene Farrell's review of the book (JAIC v. 19, no. 2, pp. 111–112, 1980). Since it seems appropriate for a review in a professional journal to include comment upon those sections of the book which overlap the interests of the profession I feel compelled to point out Chapter 15 titled “Conservation of Antiquities.”
The author, Goffer, has done a very good job of creating a sourcebook for the enormous field encompassed by the term “archeological chemistry.” Generally he has dealt concisely with the various applications of analysis in archeology and has included an appropriate introductory discussion of the physical-chemical natures of the materials analysed. A difficulty exists, however, in presenting conservation methods in the same way. The oversimplifying nature of such a sourcebook tends to provide a sort of endorsement to those techniques which find mention in its necessarily limited text. A danger exists, then, when a book directed toward an audience with responsibilities for the care of antiquities but generally lacking conservation training fails to disclaim the use of “general case” solutions. Secondarily, it would have been useful to include some comments relative to the impact of the various conservation procedures upon the types of analysis described previously in the book. Quite often the analyst may be led astray if s/he is not fully aware of the changes brought about by earlier conservation treatments on the object.
In chapter 15 there are several passages which deserve comment as they contain errors or perhaps overstate the applicability of certain methods by what they fail to mention. Specifically:
On stone consolidation—“Such compounds as silicon esters (Schmidt-Thomsen 1969), epoxy resins, and polymethyl methacrylates (Gairola 1959) have been used; the hardening they cause is so complete that no discoloration or efflorescence occurs after treatment.”—p. 268.
On pottery—“Glazed pottery is waterproof and is, therefore, very stable. Unglazed pottery, although chemically inert, is easily disrupted by soluble salts…”—p. 268. Glazed pottery is seldom so completely glazed or so free of cracks as to be waterproof or immune to salt damage. On the contrary, flaking of the glaze due to salt crystalization beneath is a common problem for some conservators.
On glass—“Most ancient glasses are of the soda-lime type. Many contain an excess of lime, which makes them water-soluble and easily damaged by moisture;”—p. 269. Precisely the opposite is true. Lime is introduced into a soda-lime glass specifically to reduce the solubility of what would otherwise be a sodium silicate or “waterglass.” In fairness it should be said that this is probably an oversight, since Goffer correctly describes the situation in an earlier chapter on glass compositions.
On glass again—“Unstable glass changes color on exposure to sunlight; it is advisable, therefore, to keep excavated objects in darkness and in a damp atmosphere and to color photograph them shortly after discovery.”—p. 270. While an excessively dry atmosphere is certainly a danger to a partially hydrolyzed glass (prone to crizzling), a “damp” environment may not be desirable either. Weeping may increase, and water, after all, is a reactant necessary for further hydrolysis to occur. While photographic documentation is desirable, the idea of preserving the glass color on color film ignores the notorious instability of color film. The photographs would require dark storage as well. If color is important enough, the piece could be photographed through color separation filters. Any sort of photography requires light exposure, however, so …
On bronze—“Stabilization of excavated bronzes may be effected by exposing them to vapours of ammonia (Thouvenin 1958, 1959).”—p. 270. Anyone who has seen bronze disease as a result of ammonium chloride flux residues on a modern copper alloy will find this disconcerting. No method which leaves chloride ion in a soluble form will provide sure protection.
On metals in general—“A reversal of the natural electrolytic process of corrosion is today the most accepted method of restoration of ancient metal objects.”—p. 271. Electrolytic reduction, which certainly is a very valuable tool for certain objects, is by no means responsibly applied so broadly as this statement suggests. Often, in fact, it is applied without adequate understanding or experience that is necessary to bring about a controlled deposition of the reduced metal.
Lastly, there is a typographical error in the glossary definition of pH, defining it as:
In summary, while Archeological Chemistry; a Sourcebook on Scientific Applications in Archeology succeeds in its main objective, chapter 15 could not possibly address the subject of antiquities conservation suitably without considerable expansion beyond its present format.JohnTwillyAdjunct Assistant Professor, Conservation Scientist, Department of History, University of California, Riverside, Riverside, CA 92521
1.1 To the Editor:
In the recent issue of the Journal (v. 19, no. 2) a reference was listed at the end of the article by Hoare and Connell, “Build your Own Vacuum Hot Table for $600,” which might lead to a wrong impression.
The reference was to my paper, “Electrostatic Hold as a Pressure Source in Lining Paintings,” in which the vacuum system is used to generate an electrostatic field between two membranes. Although the vacuum line is placed on top of the membrane, vacuum plays no part in the creation of any pressure acting on a painting.
The cross reference from one function to another can lead to an impression that vacuum, in my application, is used in lining. I hope that it is clear that air is simply being drawn through fiberglass between two membranes by the vacuum system, but no vacuum pressure is involved. This method was later much improved, as described in my paper presented at the ICOM conference at Zagreb, Yugoslavia, in 1978 (“Electrostatic Hold: a New Technique of Lining,” ICOM Committee for Conservation, 5th Triennial Meeting, 78/2/7).Robert E.FieuxFieux Restoration Laboratory, Inc., 263 Cedar Street, West Barnstable, MA 02668