Volume 10, Number 1, Jan. 1988, pp.11-14

Technical Exchange

Pigments

An analytical study of the pigments in an Indian manuscript at LACMA has led to a very rare identification of tin oxide as a white pigment. Other uses of tin oxide are well known (in ceramics for instance) and there is documentary evidence for its use as a pigment, but actual identifications are quite rare. Anyone who knows of other occurrences in specific art works or suspects that he or she has observed it before, is encouraged to contact John Twilley at (213) 857-6158.

A study of violet pigments is underway at LACMA and, in order to build a broader base of pigment identifications, John Twilley is seeking additional samples from paintings of known date and origin over the period from 1880 to 1930. At the moment only violet pigments themselves (not violet mixtures of blue and red) are of interest. If anyone has such a work for which they would like a pigment identification to be made in exchange for adding this information to the group studied previously, they should contact John Twilley at (213) 857-6158. Sample requirements are extremely small, but should be discussed prior to sampling.

Microclimate Research

Research on developing an efficient, low-cost microclimate is currently being conducted by Therese O'Gorman at the Oakland Museum. The aim is to use readily available materials to construct a sealed environment that is stable and requires little maintenance. A major consideration in the case design being investigated is that it will be easy for most museum shops to fabricate. Different types of construction materials have been investigated, including plastics, and various metals. Research is now centering on methods whereby wood can be isolated from the sealed environment. The design, which is in the final stages, is freestanding, adaptable to various configurations, and has separate accesses for artifact and buffering materials.

The prototype case now being built will be tested under the direction of Steven Weintraub, Head of Conservation Processes at The Getty Conservation Institute. The effectiveness of the seals, permeability of the materials, efficiency of RH stabilization, effects of weather stratification, and different buffering configurations will be examined. Various types of gaskets will be applied, such as rigid and fluid silicones and other stable elastomers, in order to determine which provides the best seal. A novel approach is being tried, using a vapor barrier inside the base. Steven Weintraub, John Burke, Conservator at the Oakland Museum, and Therese O'Gorman have been working on the prototype for the last two years. They will publish their findings and make the final design specifications available. Of particular interest will be that various aspects of the design are adaptable to retrofitting existing exhibition cases.

Image Processed X-Rays

The J. Paul Getty Museum is working with Olganix Corporation to establish the feasibility of using their DIGITOME process as an aid in the examination of art objects. Olganix is working with sculpture conservator Billie Milam to plan a long range project involving several sculptures and possibly some paintings in conjunction with the Paintings Conservation Department. DIGITOME is a computerized process that uses standard x-ray films to provide image data. Eight x-rays of the object, taken in a precise geometric sequence, are digitized and processed in the computer. The completed exam displays the object level by level, giving the user the ability to see features missed in a one-dimensional image or film.

DIGITOME is currently being used most widely as a non-destructive evaluation tool in the aerospace industry. The process lends itself to the analysis of any object that can be x-rayed, and therefore has a wide range of applications. Previous work with artifacts was successfully performed for the Smithsonian Institution, using the earlier, film based process, DYNATOME. Olganix Corporation is located at 18210 Sherman Way, Suite 210, Reseda CA 91335, phone (818) 345-7802.

Renaissance Bronzes

Billie Milam, Sculpture Conservator at the J. Paul Getty Museum is continuing research on fabrication techniques and characteristics of Renaissance bronzes. The project is collaborative in nature and in addition to visual examination and x-ray radiography, it includes clay core analysis by petrographic thin section, x-ray fluorescence and other techniques. Included in the project are pieces from the Getty collection and other prominent Renaissance bronze collections, including the Kunsthistorisches Museum in Vienna.

Alloy analysis by XRF is being performed by Michael Schilling and David Scott under the direction of Frank Preusser, all, of the Getty Conservation Institute. David Scott, Head of Museum Science, GCI, will assist in x-ray examination and in deciding on analytical regimes necessary for the pieces.

Dr. Chandra Reedy, at Los Angeles County Museum of Art, is doing the petrographic analysis and will be doing multivariate statistical analysis of all data sets, with the primary statistical technique being stepwise discriminate analysis. The main goal of the statistical work is to determine which technical variables discriminate between regional and/or workshop groups, and to develop classification functions using those technical features to help determine the provenance of stylistically ambiguous bronzes, a technique which she used in her dissertation research on Himalayan bronzes.

The project is supported by the GCI. Please note that this is a very long term project. The more data we are able to accumulate, the more accurate the study will be.

Diamonds

Doug Adams, at Conservation Materials, is evaluating a new abrasive material. Diamond dust has been adhered to a heavy, flexible cloth with a polyamide adhesive. It is available in a number of grits but is, not surprisingly, more expensive than sandpaper. While it sounds promising, it has not yet been used in the conservation field, so he doesn't know for which tasks it is best suited. If you have questions, suggestions, or are interested, call Doug at (702) 331-0582.

Prices Reduced

Art Angle Inc. announced that their expansion bolt stretcher prices have been reduced by 1/3. The stretcher bars are made of kiln dried bass wood and come in regular weight (3" x 1 1/16"), which has a beaded lip or a bevel, and heavy duty (3-1/2" x 1 5/16"), which are beveled.

Pricing: $32.95 base charge for 100" or smaller (perimeter plus cross bars), $1.95 for every additional 6"; $10 handling charge ($15 for packages over 5' on a side). [Prices current as of press time, but are subject to change.]

Improved Mini-Vacuum

The Textile Conservation Laboratory at LACMA has just acquired a low suction mini-vacuum that runs on 110-volt power, not batteries. It is much quieter than some of the battery operated devices currently in use. It is called the "System Sweeper" from Micro Computer Accessories, Inc. It is available through:

Reliable, The Office Supply People
1001 West Van Buren Street
Chicago, IL 60605
(800) 621-4344

Refer to their 10/1987 catalogue, #27455 System Sweeper, $39.95.

Uv Mini-Lamp

A battery powered long wave Ultraviolet lamp is said to be 1/2 the size and just as bright as previously offered mini lamps. The lamp measures 2-1/4 x 3/4 x 6-1/2 inches and is powered by 4 "AA" penlight batteries (not included). The price is $44.00, including shipping.

Environmental Monitoring

Science Associates, Inc., a subsidiary of QualiMetrics, has announced availability of six products for monitoring the environment in galleries, libraries, and museums. The products are: Hygrothermograph ($470); digital Humidity / Temperature Indicator ($875); Illumination Level Meter ($550); Ultraviolet Light Monitor (Crawford), available in 0-1600uW/lumen ($620) and 0-300uW/lumen ($940); Battery-Operated Psychrometer ($145); and a Temperature / Humidity Dial ($60).

Toys

Seen in "Intellitoys", an "Archaeology Kit". The kit encourages the user to: "Dig - Discover - Display", and explains that: "An archaeological excavation will rarely produce undamaged and intact objects. Pottery is normally broken into numerous pieces and has to be reassembled and restored. This kit contains the fragments of a 1600 year old Roman vase. Carefully excavate the pieces of pottery which are imbedded in clay. Then restore the antique vessel and display this authentic replica of an ancient piece of art." The toy is manufactured in West Germany and comes in Etruscan Tomb, Pompeii, and Ancient Greece models, in addition to the Roman Vase. The Roman Vase was selling for $31.99.