Volume 19, Number 1 .... January 1997

Technical Exchange

Dean Yoder, Column Editor

Monofilaments, Monofilaments, Monofilaments!

For those of you who are always on the lookout for something to add to your bag of tricks, I may have found a few new necessary additions. Over the last several months I have been contacting the manufacturers and distributors of colored monofilaments to locate Qq!some new materials for use in the installation of objects in upcoming exhibitions at the UCLA Fowler Museum of Cultural History. Jo Hill, Director of Conservation, has sometimes been unsatisfied by the traditional clear monofilaments and asked me if I could locate colored lines more suited for use on objects in the Fowler's collection. I contacted over two dozen companies, about half of which provided samples and product information. The most exciting discoveries were a " Cam-o-flage " monofilament produced by Cortland Line Company, Inc., a "moss green" fishing line manufactured by Izorline International, Inc., and a "chameleon" monofilament distributed by Jatra International. These monofilaments, in addition to other colored lines available at fishing tackle stores or directly from the manufacturer, are just the ticket to facilitate a secure and invisible attachment to/around mounted objects.

The camouflage monofilament produced by Cortland Line is available in the 4 - 30 pound test range and has alternating transparent segments of green, tan, light brown and dark brown. Each segment is approximately 20 cm in length and blends to the neighboring shades. Cortland Line Company, Inc., can be reached by calling (607) 756-2851.

Izorline's "moss green" monofilament is produced in the 2 - 500 pound test range and is transparent grey-green in color. For additional information call (310) 324-1159.

A semi-transparent dark reddish-brown line is distributed by Jatra International under the trade name "Maxima Chameleon." It is available in the range of 1 - 40 pound test. Jatra International can be reached at (714) 380-7444.

Samples of these monofilaments, as well as samples of all the other lines collected and some product information, are on file in the Conservation Department at the Fowler Museum. The Conservation Department can be reached by calling (310) 825-1146.

Please note: All these monofilaments are nylon and appear to have stable colorants/dyes; however, be sure to test for color stability before use.

Paul Pihl

New Work Light

Over the past two years, one of the Senior Art Technicians at the National Gallery of Art has been working with a company in Maryland to develop a reliable and reasonably priced work light for examination and minor conservation treatment work in the storage and prep areas of the museum. After a prototype and two subsequent improved versions, Quatrefoil Associates (2201 Kinghouse Road, Silver Spring, MD 20905, 301-236-4200) is ready to market a fluorescent lamp they call the Conservator's Light Trolley, a high output, color balanced light source mounted on a counter-balanced floor stand. The lamp is well made, quite nice to work with, and will undoubtedly prove to be a useful tool for conservators in search of that perfect inpainting light for those dark and cloudy fall-winter-spring days ahead.

Jay Krueger

Nifty New Clamps

American Tool Companies, Inc., makers of the popular and distinctive black and yellow, pistol grip, "Quick-Grip" line of bar clamps, has a new smaller version on the market that I have found to be very useful.

Many members will be familiar with their original line of clamps, the smallest of which was the 6" "Mini Bar Clamp" (model # 00546). The new clamp looks exactly the same as its larger cousins with the exception that it is of much lighter weight, has a maximum spread of 4.75", and is called the "Micro Bar Clamp" (model #53006). Although it does not have the strength of the larger clamps, it is certainly adequate for those smaller, more delicate jobs where firm pressure is still needed.

The pistol grip type of tightening device that makes the larger clamps so easy to use has been exactly replicated for this smaller version. An indication of its size comes from the fact that instead of using your entire hand to pump the grip of the larger version (alright, I have small hands!), the Micro Clamp grip has room for only two or three fingers. I am now using these new clamps in place of my old, finicky little C clamps whenever possible.

You might not find them in the clamp section of your hardware store because - as a staff member at my local Home Depot told me - "they tend to disappear", so they are located at the check out. Also try craft supply stores.

J. Claire Dean

Tear Mending on the Suction Table

Mending tears can be one of the more difficult tasks in paintings conservation. Many of us have tried powdered nylons, strands of Acryloid B-72, reweaving, dotting epoxies, etc., to provide a hard resilient bond, which in theory, can be reversible. Most tears fail (lift up) because the fill which bridges across the paint layer is not strong enough to accommodate the strain of re-tensioning or restretching, even if the support fabric is superbly mended.

I have found the following method helpful. After the usual preliminary consolidation, realignment, and humidification procedures are complete, the painting is placed on the suction table or over a small suction platen. A layer of Hollytex, or perforated silicon mylar is placed underneath. (Rob Proctor uses a pattern wheel to create the perforations). A dilute mixture of (HMW) poly vinyl alcohol (4 % in water) with a little added calcium carbonate (or gypsum), is introduced into the tear while the suction going.

The suction is doing several things at this point: it is drawing the adhesive into the structure of the fabric; it is holding the support fabric completely in plane, and rapidly drying out the adhesive.

The lacuna can now be filled with a poly vinyl alcohol/calcium carbonate mix which is the consistency of a typical filler. This filler can be made by taking an 8% stock solution of (HMW) PVOH and sifting in calcium carbonate (or gypsum) until the consistency resembles a sticky paste. The filler is dabbed into the lacuna with a brush or spatula as the suction continues to draw it in. Several applications are necessary as this mixture tends to shrink.

The fill is leveled with the usual methods, a soft, damp sponge, for example. The suction is left on until the filler is dry. The result is a firm and rigid fill similar to the hardness of an old paint layer, which does not exhibit any tendencies toward lifting when the support fabric is re-tensioned. Typically a small sized linen/Beva film patch is attached to the reverse of the tear for added support.

Dean Yoder

New Material for Hanging Textiles

The Small Corporation (Greenfield, MA) now makes a powder-coated aluminum slat (3" wide) with 2" Velcro along one edge and countersunk holes along the other edge as an archival and affordable option to the "Velcro stapled to a wooden slat" for hanging textiles. The slat is only 1/8" thick. The cost (as of 7/96) is $6.50/foot with a 4 foot minimum, shipping extra. Other options are available including keyhole shaped holes, no Velcro and a hanging cleat for use with the slat. The Small Corp. can be reached at P.O. Box 948, Greenfield, MA 01302, (413) 772-0889 or (800) 392-9500.

Margaret E. Geiss-Mooney

Carpet Damage from Routine Maintenance Procedures

The response to my presentation at the Las Vegas meeting about the potential and actual damage to carpets caused from routine maintainance procedures (abstract on pg. 17) was greater than I expected, and suggests that it might be a significant problem in many institutions. To briefly summarize, I reported on my observations of two galleries over a number of years where carpets were used as part of permanent displays. Though the carpets were behind ropes, and the public did not have contact, I observed an accumulating amount of soiling, fraying, and general deterioration along the edges. The surface of the carpets also seemed to have a fine "coating" of sticky bluish fibers. This, added to the appearance along walls, on furniture legs, and sculpture bases, of abrasion marks, pointed to maintainance equipment as the source of the problem.

Further investigation confirmed that routine maintainance carried out in a careless manner was responsible. Floor wax obviously was being applied to the surrounding wood floors without protection of the carpets, buffing machines were rubbing along the edges, and floor brooms that had been sprayed with anti-dust chemicals were pushed over the carpet surface.

Education of maintenance personnel along with regular supervision would be an obvious solution, but it is difficult for a number of reasons. A lack of a specific training program, turnover in personnel in these generally lower paying jobs, off-hour work when supervisory staff is not present all contribute to the problem.

In this particular case an attempt to control damage was made by placing a 3/4" x 1" molding (to match the floor) approximately 3" away from and parallel to the edges of the carpet. The premise being that it serves as a barrier to equipment, and at the least will make the buffers and brooms ride up above the carpet edge.

It has not been in place for very long and it is difficult to say that it is the perfect solution, but it does seem to be helping. However, one noticeable problem is that the protected edge just behind the molding seems to catch dust which, if not vacuumed at some regular interval is noticeable.

I am interested in just how common this problem might be, and so would be interested in hearing from any reader who observes this problem. I can be reached at the following address:

343 Soquel Avenue #41
Santa Cruz, CA 95062
(408) 426-2118
e-mail Stan@raven.bc.ca

Stan Derelian

Bleaching Twentieth Century Papers

In an attempt to evaluate bleaching procedures on modern and contemporary papers, I have been studying the fluorescent whitening agents (FWA) or optical brighteners used as dyes in these papers. These dyes have been incorporated into paper manufacture since 1939 and can be found in many twentieth century papers.

Their chemistry is both very interesting and problematic for conservation treatments. The industrial literature states they have poor stability to peroxides and chlorine bleaches. They require some U.V. light to excite the dye molecule to fluoresce and perform as a whitening agent. However, too much U.V. (or peroxide or chlorine) degrades the dye. When the c=C bond of the central stilbene molecule (the most common FWA) is broken, it changes the form of the molecule from the low energy TRANS-form to the high energy CIS-form which doesn't re-emit in the visible range.

I am interested in knowing if the "color reversion" and "lignin" darkening reactions associated with hydrogen peroxide bleaching and light bleaching respec-tively (both oxidative processes) are due to changes in these dyes rather than other explanations.

In some preliminary tests, I bleached "Somerset" paper with both hydrogen (oxidizing bleach) and sodium borohydride (reducing bleach). In visible light, both looked equally good. However, there were dramatic differences when examined under ultraviolet light. Under U.V. the hydrogen peroxide samples had turned brown and even showed the swirl patterns of the solution as it first touched the paper, as well as shadows of other paper samples placed on top. In contrast, the sodium borohydride sample looked uniformly bright with an even fluorescence.

I have begun testing other papers with mixed results. My query: should we be using reducing bleach on papers with FWA dyes, and are we degrading these papers by using oxidative bleaches? For now, I carefully examine 20th century papers under U.V., do a spot test with any bleaching solutions, and examine those test areas under U.V. prior to treating.I am interested in collaborating with others who have similiar experiences or are interested in this topic. You can contact me at (209) 323-8578 or adwan.wco.com

Antoinette Dwan

Miscellaneous

This is a collection of useful bits I've been saving to fill out a column.

The first is a tough and versatile tool variously labeled as a glazier's or painter's tool. It is usually found near the putty knives as it is meant to be used for puttying windows. It is distinctive in having a beveled edge that goes to a point at one side. This tool handles many prying and scraping jobs and takes an amazing amount of abuse without losing its smooth clean edge. This is the very best tool I've used for levering nails out of a stretcher bar without marring the tacking edge.

The next is an extremely useful application for a soot removal sponge, available from a number of suppliers and recently the subject of a flurry of postings on the Distlist. I've found that it is a very effective tool to remove the last ghostly residue of fill material surrounding fills. Besides being quick and easy it is DRY, which means that you don't risk eroding the edges or the texturing of your fill. One should keep in mind when finding uses for these sponges that one contributer to the Distlist stated that they may contain a very, very small percentage of detergent.

Conservation Support Systems carries a German dusting brush made from sheep hair which is ultra-soft and costs only $7.71. The brush area is 1" by 5" with a 4" handle. It sheds a bit but is soft enough for delicate surfaces. I've contemplated buying a batch and giving them to favored clients or those inclined to use something worse to dust their art. Scott says he'll talk discounts.

And finally, a really low tech solution to securing easily tipped beakers, jars, etc., especially useful in on-site situations. Set them inside a roll of masking tape or better yet a nice fat roll of duct tape. Very effective for preventing spills.

Carolyn Tallent