Volume 11, Number 2, May 1989, pp.11-14

Technical Exchange

Walter Henry, column editor


To those of you who after reading Sharon and Chris's article nevertheless retain an atavistic desire to play in the two-dimensional fields of Teas diagrams; who perhaps out of nostalgia for the old pre-revolutionary days or respect for a venerable teacher of the old school still find yourself scratching away on triangular graphs with pencil and ruler, TeasTime may be of some interest.

TeasTime, a computer program for IBM PC's and compatibles, is intended to do away with some of the drudgery of solvent selection by the Teas method. Simple to use, you specify a set of fractional solubility parameters for your target solute, give an indication of how wide an area around your target will be acceptable and TeasTime will think backwards (much like its author) to determine what blend of solvents will match those parameters. TeasTime also knows about a handful of solutes (you can easily add more) so in some cases you don't actually have to make those totally random educated guesses about your target parameters. It is also simple to customize the solvents database to limit the search to those solvents you like working with. At present TeasTime only finds blends of two solvents, but a future version will also find blends of three, for those of us who have to justify large material budgets. TeasTime is available at no cost, from its author (50% discount for WAAC members). Send email to: whenry@lindy.stanford.edu or otherwise contact:
Walter Henry, Preservation Dept., Green Library, Stanford, CA 94305; 415-725-1140.

Walter Henry

Solvents, Part 7: Solvents for Bocour Magna Paints

A less toxic solvent than the commonly used xylene or toluene for Bocour Magna paints can be made by mixing acetone and naphtha or mineral spirits. Acetone alone usually evaporates so quickly that inpainting is difficult. The addition of the hydrocarbon solvent slows down the evaporation to a usable rate. Depending on the substrate and desired effect, the proportions of the acetone and naphtha may vary from approximately 1:4 to 4:1. Increasing the naphtha or mineral spirits results in a richer feeling to the paint and a slower drying paint layer. When there is too little acetone in the mixture, the Magna paint will become gummy and clumpy. Due to the rapid evaporation of acetone from the solvent mixture, this gummy condition may be experienced by the conservator, who simply adds more acetone to overcome the problem. (See Feature Articles for an explanation of this problem.) The evaporation differential has not been observed to be a problem once the paint layer has been applied to a surface. The only time this mixture has been found to be a pain in the neck was during the inpainting of outdoor sculpture on a hot and windy day, when reversion to toluene was necessary. Try it, yer liver will love ya!

Sharon Blank, No Teas-ing Institute, Los Angeles County Museum
of Art

Conservation Materials, Ltd.

Doug and Dorothy Adams have released a new price list in a new format. Items are listed in two separate lists, by catalog number and alphabetically by description. New products are highlighted in the center of each page. Also new, Conservation Materials now has a 24 hour FAX machine, (702) 331-0588. In keeping with our solvent theme issue, products of special interest are triethanolamine (100%, not the common 85% pure), benzyl alcohol, and a new suite of enzymes. The enzymes, from Novo Laboratories in Denmark, are a lipase, a protease, and a cellulase.

Lipolase is a lipase, an enzyme that catalyzes the hydrolysis of the triglycerides found in polymerized oil films. Formulated for use in automatic laundry detergents, the enzyme has a working range of pH 6-11 (twice the activity at pH 11) and maximum activity at 35°. C, although activity is strong from 20-60 °. C.

Alcalase is a protease, a protein hydrolyzing enzyme, usable in the pH 6-10 range. It is designed to break down all kinds of proteins including hemoglobin. Celluzyme is a cellulase, an enzyme designed to hydrolyze cellulose to lower glucose polymers. Its recommended range is pH 4.5-6.0.

The handling precautions for all the enzymes should be studied and followed.

Also highlighted is the full line of Bocour Magna colors, 31 flavors plus the Medium and Magna Varnish.

Klucel GF, hydroxypropyl cellulose, dissolves in water, as do other members of the chemically modified cellulose ethers, but is also soluble in organic solvents like ethyl alcohol, methyl alcohol, acetone:water (9:1), toluene:ethyl alcohol (3:2), or methylene chloride:methyl alcohol (9:1).

Quator, pronounced water, is a cotton fabric impregnated with a mixture of tallow, mineral spirits, and ultrafine aluminum oxide abrasive used for polishing brass, copper, bronze, and aluminum. Syringes and needles--not for medical purposes, they are not sterile--are now available. Syringes, in packages of 40, are in 5 ml, 10 ml, and 20 ml. Needles, 12 to a box, range in size from 18 gauge, the finest stocked, to 13 gauge.

Doug is also carrying: Milliput, a superfine, white, two part epoxy putty; sodium borohydride, the bleach; bead silica gel in a new form, 1/8" beads that flow freely and are less prone to fracture; and Hxtal Crystal Plus, a modification of the original Hxtal epoxy to yield a slightly slower curing, clearer product that can be used in large batches without overheating.

Other highlighted products include Carusorb, orthophenyl phenol, B-67MT, 2 1/2 gallon plastic can of Stoddard solvent, Chinaglaze ceramic glaze, oleic acid, and the Art Sorb cassette, all discussed in previous technical exchanges.

Infrablack--The Blackest, Black Surface

A micro and macro-textured black surface has been developed for use in the next generation of space telescopes by Stephen Pompea of Martin Marietta and Steward Observatory. The surface, etched and anodized onto aluminum, has a reflectance of less than 1% under ultraviolet and visible illumination; that's black. The material makes everything you thought was black appear gray by comparison, including carbon black and diamond black (an aniline pigment). The surface looks like black velvet, but a velvet that has a texture so fine that the surface seems out of focus.

The trick to creating such a surface is to first create a random, macro-texture (with 500 micrometer features), by etching the aluminum surface. The surface is then micro-textured (at the 10 micrometer scale) in the anodization process in which small steeple shaped projections of aluminum oxide are grown onto the surface. The surface is dyed with a black aniline dye, then treated to "seal" the dye beneath a new form of hydrated alumina. The resultant surface is resistant to chemical attack like most aluminum oxides. It has flown on the space shuttle and exhibited resistance to more exotic attack from atomic oxygen. The material does have some limitations. The surface is very fragile and expensive. As the process relies on anodization, it can only be applied to aluminum alloys and works best on 6061 alloy.

Stephen Pompea is looking for innovative and or artistic applications for this material. For more information, contact him at: Steward Observatory, The University of Arizona, Tucson, AZ 85721, (602) 621-6523.

Chris Stavroudis

Frank Joel

Just a short note to bring to the attention of the WAAC Membership the fact that Frank Joel Ltd. has recently gone out of business. Joel was used as a supplier by some folk in the USA, especially those of us who do archaeological field conservation in the Old World.

Their stock and general business has been taken over by an already existing company in the U.K. called Archival Aids. I have received very encouraging correspondence from Archival Aids management. Unfortunately, they are cutting back on Joel's catalogue, and they will not, for the present, be carrying as wide a range of materials as Joel used to. However, they should still prove to be a useful point of supply on the other side of the Atlantic.

Their address is: Archival Aids, Ltd.; P.O. Box 5; Spondon; Derby; DE2 7BP; United Kingdom; Tele: (0332) 6664000, Telex: 377769 PPCHEM.

Claire Dean

Microclimate Research at the Oakland Museum

Practical methods for providing stable environments for exhibit and storage of artifacts have received increased attention lately in an effort to prevent deterioration from formaldehyde and other pollutants, and as an alternative to expensive local HVAC systems.

Several years ago, the Oakland Museum began using MarvelSeal 360 to seal exposed plywood or particle board case elements. MarvelSeal 360 is a polyethylene/aluminum/nylon laminate film which has been used extensively as a waterproof, vaporproof, flexible barrier for the storage of sensitive military and industrial materials (and making bags for freeze-dried backpacking foods). It can be easily heat sealed to itself and has an extremely low vapor transmission rate. In practice, case decks, liners, and risers are completely sealed in a tight- fitting bag of MarvelSeal, after which they are wrapped in an appropriate washed fabric. Rather than rebuild all the 20-year old cases in the galleries, they have been retrofitted in this manner to exclude harmful off-gassing. A recent traveling exhibit of over 350 California silver artifacts was prepared in this manner and fared very well over its one year journey.

An extension of this work led to the development of the low cost microclimate that Therese O'Gorman, assistant conservator, has been working on in concert with Stephen Weintraub and the Getty Conservation Institute. That two year research project is now nearing completion and the results are expected to be published this year.

A further development has been research into possible storage microenvironment made with MarvelSeal 1177. The 1177 film, a polyethylene/fluorocarbon laminate, has similar properties but is an even better vapor barrier than the 360, with the additional advantage of being clear. In practice, a bag is made large enough to accommodate the artifact along with a soft container of conditioned silica gel. The artifact and buffer are inserted and the bag is sealed closed. In this way the environment should stay constant and the object can still be observed. Access to the artifact is made by cutting the bag which could then be resealed several times. In tests where a recording hygrothermograph was enclosed in this manner, humidity variations were less than 3%, even though the bag was subjected to refrigeration and rooftop summer sun and rain. In another test, a small bag containing completely desiccated indicating silica gel was sealed inside another bag less than half-full of water. Over a period of six months, the desiccated silica gel in the inner bag has shown no change in color from blue to pink, i.e. no increase in moisture content, and the water level in the outer bag has remained constant.

Further tests are being directed to filling the bags with nitrogen or argon gas instead of air, incorporating activated charcoal along with the silica gel buffer, and testing the air quality of some aging empty bags for potential inner pollutants. If all goes well, an efficient storage microclimate might easily and quickly be fabricated for less than the cost of lunch.

John Burke, Conservator, Oakland Museum

Insect Pins
Ultrasonic Cleaners

Insect pins, used in textile conservation and other applications, have been viewed by conservators with some suspicion, as they are coated during the manufacture process with oil. An effective cleaning method is sonication in 2-3 changes of acetone. Ultrasonic cleaning devices are useful tools in all areas of conservation and are commercially available at local hardware stores. One model is Denta Plus (ultrasonic denture cleaning system) #DP120, for $37.90, distributed by Adray's in Los Angeles (Adray's code #109711) or by the manufacturer, Connoisseurs Products Corporation, Sommerville, MA 02145.

Jo Hill, Los Angeles County Museum of Art

A Tip: How to Locate Things

The Thomas Register is a multi-volume compilation of company profiles, catalogues, products, and services. Published annually, the volumes can be a tremendous resource for conservation, as they can essentially serve as a business-to-business "yellow pages" for the entire United States. Imagine having a list of 20- 500 companies who offer cellulose acetate sheets, dental instruments, or special adhesives, or.... The 1989 set can be found at local universities (UCLA School of Management library, USC Management library) or public libraries (Fairfax, Beverly Hills, Hollywood branches in L.A.). Some institutions may have a set that is a year or so out of date; these are just as useful.

Jo Hill, Los Angeles County Museum of Art

Disfigured Leather Artifacts

Bob McGiffin is interested in communicating with conservators who have analyzed and/or treated leather artifacts with whitish disfigurements. These disfigurements are frequently observed on leather garments and tack. Please contact: Robert F. McGiffin, Chief Conservator, Gene Autry Western Heritage Museum, 4200 Zoo Drive, Los Angeles, CA 90027, (213) 667-2000 or (619) 723-2578.

Robert F. McGiffin

Fire Extinguisher System Inquiry

The Gene Autry Western Heritage Museum recently requested the loan of several paintings to supplement an upcoming exhibit. As part of the request, the necessary facilities report was submitted to the lending institution. The Museum easily passed all of the requirements except for one. That requirement was a dry pipe or no pipe fire extinguisher system. While the Gene Autry Museum understands the possible problems associated with a wet pipe system, it is required by law to maintain such a system.

We are interested to hear from other museum professionals at institutions that have been denied artifact loans due to existing fire extinguisher systems. Please contact Robert F. McGiffin at the address listed above.

Robert F. McGiffin

Hiromi Paper International

As of April 1, 1989, Ms. Hiromi Katayama, formerly of Infusion, Ltd., will be conducting business as Hiromi Paper International. The company will continue its practice of providing its customers with the highest quality Japanese paper at competitive prices. The company is devoted to the creation of a greater rapport between Japanese paper makers and artists, conservators, designers, book makers, and printers. They are also interested in providing paper for conservation work and in further developing a communication network between its customers and Japanese preservation specialists. Hiromi Paper is willing to experiment with the creation of custom-made paper, too.

For further information on orders or on special projects and collaborations involving Japanese paper-making techniques contact: Hiromi Paper International; c/o Royal Ren Co.; 409 Santa Monica Blvd., #225; Santa Monica, CA 90401; (213) 395-2058; FAX 393-4942.

 [WAAC]  [WAAC Newsletter]  [WAAC Newsletter Contents]  [Search WAAC Newsletter]  [Disclaimer]

[Search all CoOL documents]