Volume 6, Number 2, May 1984, pp.15-16

Technical Exchange

A microscope slide mounting medium with a refractive index of 1.662 but which contains no PCB is soon to be available from R.P. Cargille Laboratories, Inc. The product is called Cargille Melt Mount 1.662. Although it is available in other indices of refraction, conservators will probably wish to use the 1.66 product if their reference samples are mounted in Aroclor 5442. I received a sample of Melt Mount in April 1983 and have found it very similar to Aroclor 5442. Inquiries about the product should be addressed to:

    R.P. Cargille Laboratories, Inc.
    55 Commerce Road
    Cedar Grove, New Jersey 07009
    Technical and Material Data Sheets
    are available from the company.

BHT Implicated in Textile Yellowing

The results of investigations concerning the yellowing of stored textiles reported by Du Pont chemist KENNETH C. SMELTZ at the Atlanta meeting of the American Institute of Chemical Engineers should be of interest to a wide variety of conservators. As reported in Chemical and Engineering News (March 26, 1984, pg 27) Smeltz has implicated the common antioxidant butylated hydroxytoluene (BHT) and environmental nitrogen oxides in the formation of yellow 2,6-di-tert-butyl-1,4-quinone methide. This presumably happened during the storage of newly manufactured cloth.

Photograph conservators have been concerned for many years about the migratory potential of BHT or its analog butylated hydroxyaniline (BHA). When added to increase the oxidation resistance of polyethylene or polypropylene it was felt that it might transfer to photos enclosed in otherwise acceptably stable polymer.

Because nitrous acid is formed as a by-product in the formation of the yellow quinone methide, alkaline conditions which neutralize this acid favor increased yellowing. While his recommendations for the use of polyethylene free of BHT and for reduction of nitrogen oxides in storage facilities are admirable, Smeltz has taken the one-sided view that textile finishers should use citric or glycolic acids to finish fabrics to an acidic state. No mention is made of whether these would be intended to be washed out at a later date or if they might cause unforeseen problems of their own.

Query

For a research project on solvent-resin solubility parameters, I am seeking information on personal applications of solubility charts, interesting examples of solvent reforming, swelling and leaching of coatings, as well as obscure references to solvent varnish film interactions. French and German materials in addition to those in English will be appreciated.

Have any WAAC members had any experience with the coating material called "Vandal Guard?" A San Diego artist has coated his outdoor paintings with Vandal Guard and they have developed serious condition problems which appear to be directly related to the coating. A law suit filed against the manufacturer of Vandal Guard is pending. Any information that the membership can provide would be most helpful. Please contact either: Betty Engel, BACC, P.O.Box 3755, San Diego, CA 92103 or Michael Schnorr Fine Arts Department, Southwestern College, 900 Otay Lakes Road, Chula Vista, CA 92010.

Fine Art Support Systems have a unique expansion bolt stretcher bar made of poplar. These museum quality stretchers can be custom made within three days of receipt of the order; so turn around time is reduced to a minimum. They are also making easels of oak and brass. These easels are exceptionally functional as well as being aesthetically superior. This is a young company which is putting quality and service first. The address is: Fine Art Support Systems, 266 South 1015 West, Orem, Utah 84058 (801) 224-6329