West Lake Conservators Mural Conservation

THE SUCCESSFUL USE OF SOFT FACED MONOMESH AS THE LINING SUPPORT FOR A 14' x 17' MURAL
Paper given by Susan S. Blakney at AIC, Denver, Colorado 1993
Printed in AIC Painting Specialty Group Postprints 1993

Susan S. Blakney, Fellow AIC, IIC
Senior Paintings Conservator
West Lake Conservators, Ltd.
Tel: (315) 685-8534

Photos and More Information on Murals Conserved since 1975

In 1981 Margaret Sutton and I from West Lake Conservators Ltd. began a search for synthetic fabrics suitable for the lining of paintings. After two years of testing lining adhesive systems, with collected samples, in a variety of combinations, we presented our findings at the 1983 AIC Conference, in Baltimore. Our Poster Session was titled "A Sensual Lining Comparison". This resulted in the introduction of Terytex®, a 100% polyester multifilament plain weave, which has now been used as a lining support in many labs across the United States.

Another ideal support fabric we discovered was Monomesh, an unusual material which meets the desired characteristics for lining canvas murals or oversized paintings, and also has potential for numerous other conservation applications. Available in many styles, in widths up to 390" (32.5' ), its stiff yet flexible and porous characteristic offers a semi-rigid support which lends itself to a variety of lining and installation techniques.

We selected Soft Faced Monomesh, style SE-8334 (Fig. 1) as an ideal support for the lining of oversized paintings. This two-ply weave (recently renamed Monotex) is composed of rectangular cross section polyester monofilament yarns in the machine or warp direction, and a combination of monofilament and spun acrylic yarns in the cross- machine or weft direction (Fig. 2). Both polyester and acrylic are chemically inert and have resistance to changes in temperature, relative humidity, moisture absorption, rot, microbial attack, and organic solvents.

The fabric ranges from 3.5 to 4.5 oz. per square foot. Its tensile strength is 1,100 lbs/inch to break, with elongation of 23% at break. Its permeability of 25 CFM is an advantage as an air conduit in vacuum applications, and for ease in reversing adhesives with direct application of solvents through the reverse. The spun yarns incorporated in the face of the fabric together with the special weaves employed, result in a very smooth and soft contact surface. The fuzzy nap offers strong adhesive attachment (Fig. 3).

Manufactured by an established international company, SCAPA Inc. (Forest Products Division, Waycross, Georgia) as a dryer fabric, Monomesh is used in the paper industry to create a non-marking surface in the drying of paper sheet. Monomesh belts run at high speeds (up to 50 mph), have excellent wear resistance and a high heat tolerance (285 F. acrylic and 300 F. polyester). The rectangular yarns give the fabric increased stability and resistance to bowing on the paper machine.

Also available are flawless Y-Pin seams, designed to be non-marking. This allows the fabric to become endless, and create a sharp angled bend. The fabric can be easily rolled for transit or storage. It can be cut with heavy scissors and the edges heat-sealed to prevent unraveling. Monomesh is woven on high tech looms to precise speci- fications, resulting in absolutely smooth dryer fabrics with a high degree of repeatability, which are designated with an "ISO 9001" International Quality Standard. SCAPA's "Total Quality Commitment Program" makes customer satisfaction a priority, and custom orders are welcome.

In 1986, our first proposed use of this fabric, to line a group of badly cupped, oversized oil on canvas paintings, did not materialize due to funding problems. We did, however, vacuum line with Beva 371® adhesive, a formerly cut out section of one painting, to be used for fundraising purposes, to demonstrate how the paintings could be stabilized and as a test for monitoring the corrected surface plane. No weave interference was detected, and the vignette remains stable seven years later, although displayed in a harsh uncontrolled environment. Excited by the prospects of Soft Faced Monomesh, Margaret Sutton and I presented the fabric at the 1986 AIC Conference in Chicago. We were too late for the abstract to be included in the Pre-Prints. This limited introduction was titled "Soft Faced Conserve Monomesh, A Possible Lining Support For Oversized Paintings". Due to the infrequency of treatments of this nature, it wasn't until several years later that we had the opportunity to employ Monomesh as proposed.

In March 1990,West Lake Conservators were asked to save a 14' x 17' WPA-era mural, which was doomed to destruction by scheduled renovation. The mural was designed and painted by Virginia True in 1937. It depicts the mission of the College of Human Ecology, where it is located at Cornell University, Ithaca, NY. Our team was composed of associate conservators Margaret and John Sutton, apprentice Kennis Howard, and myself. With just over a month's lead time, we planned and completed its removal during the college's 5-day spring break.

The painting was executed in low profiled oils upon a heavy weight canvas with a thin oil ground. The canvas was glued tightly, to a plastered, concrete wall, with a water based adhesive. A simple strip molding covered and framed the outside edges. It was located 10' from the floor, above a black board, in a two-story amphitheater with very cramped floor space, and limited access through a narrow corridor, off of a hallway. This necessitated precise calculations and planning to accommodate equipment and the removal of the rolled mural (Fig 4).

Block and tackle, rented from our local sailboat shop, was secured by a Cornell maintenance crew to ceiling beams, approximately four feet from the wall, beyond the ends of the mural. The space age fiddle blocks (500 lb. test) with ball bearings and jam cleats, made relatively easy work of lifting and securing heavy weights. Electric Genie lifts proved the only means of accessing the mural repeatedly from top to bottom with ease, while allowing necessary clearance to roll the mural. Limiting toxic exposure was a major priority when selecting all of the materials. The possible effects of toxic vapors was thoroughly considered, both to ourselves and to others within the building. A protective working varnish of Soluvar was applied by brush from top to bottom. Next a paper facing of wet-strength tissue cut roughly in 16" squares, was applied with wheat starch paste.

Wide tabs of Beva® impregnated fiberglass cloth and Terytex®, were wrapped around an existing 1/2" diameter metal cable, which was stretched along the ceiling and top edge of the mural. These tabs were heatset onto the faced mural, with Beva® film adhesive and hand irons. This precautionary measure was taken to safeguard against the mural falling during separation. Simple tools of varying lengths were cut from scraps of G10 phenolic resin plate. Two layers were taped together quickly, with double sided tape, for increased rigidity of the handle section, and the tips were beveled with a file. These extended our reach, and facilitated separating the canvas from the wall.

Once the bottom 1/4 of the mural was separated, wide leader tabs of Beva® coated fiberglass and cotton duck were heatset in place, with Beva® film adhesive and hand irons. The other ends were stapled to the tube and covered with tape. These leaders allowed the mural to be rolled without crimping the painting, while lifting the mural away from the wall, thus creating space to continue the separation. A 20"-diameter Sonotube® on which the mural was to be rolled, was prepared by covering the outside with acid-free blotter secured with double-sided tape. Two layers of 3/4" thick plywood were cut into circles matching the inside diameter of the tube, glued and screwed together. Holes were drilled through the centers, and the prepared templates were inset 6" into each end of the tube, and screwed securely in place with flathead wood screws. A 3-section 2" galvanized pipe was run through the tube, and floor flanges were screwed onto the threaded ends. The tackle was tied to both ends of the pipe; the roller was lifted off the floor (Fig. 5).

Cushioning cardboard was taped to the outside edges of the Genie lifts to protect the rolled mural from contact. Working from the bottom edge, behind the canvas, the mural was slowly separated. Plaster debris fell clear of the roll as the separation progressed. When the mural was detached halfway, it was rolled by hand onto the tube, as it was lifted higher by ropes from the floor (Fig. 6). Again the Genies were indispensable in adjusting our working platforms with ease. When at last the mural was free, the tube was lifted to the ceiling as the last section was rolled on. We cut the safety tabs and lowered the tube to 4 x 4 standards resting on dollies.

After sawing excess ends off the tube, four men maneuvered the rolled mural through the corridor, into the hallway, through exterior doors, and back into a nearby auditorium. Here the mural was unrolled face down onto a sheet of polyethylene, to scrape off excess plaster and vacuum the reverse.

Wide strips of polyester needled felt were joined together with Beva'd® glass fabric, to create a single sheet of cushioning interleaf for storage. The leader tabs were repositioned, and the rolled felt was laid across a row of chairs behind the tube. Rolled strips of glassine were laid beneath it on the floor, and the ends of all layers were secured to the tube with staples and taped over. The mural was re-rolled onto the suspended tube with both glassine and felt protecting the paint layer. Wide bands of Terytex® were taped in place to secure the roll, and it was covered with polyethylene for indefinite storage.

Three months later a new location was obtained for the mural, and we transported it to our lab for STAGE B consolidation, cleaning, lining and inpainting. Additional work space was rented within our building and the mural was unrolled face-down on a smooth floor covered with clean polyethylene. A low work platform was created, with two poly-covered 16' 2x12's, with ends resting atop dollies. This allowed easy access to all parts of the reverse, for removal of excess adhesive and irregularities, prior to lining. The reverse was consolidated with two separate penetrating applications of Beva 371® adhesive, diluted with VM&P Naphtha 1:4, applied with paint rollers on extension handles and dried before re-rolling and unrolling face up.

The protective facing was now carefully removed. No areas of paint were delaminated and the paint/ground layer was generally sound. Removal of the working varnish and excess Beva® was accomplished with VM&P Naphtha and Varsol-1 (Exxon). Traces of a slight grime layer were removed with a mild soap solution. We decided to line the painting in our studio, within a vacuum envelope, atop a modular lining table. The heated section was created by adjoining our two hot tables together, and adding a drop-leaf to one (Fig. 7). An overall extension was created by nailing a 2 x 4 ledge along the length of the tables, onto which the ends of foamboard sheets were stapled; their other ends laid atop the poly-covered platform planks, which rested on top of other studio furniture and books. Staples and tape easily secured this extension, creating a table 14' x 17'. A single sheet of polyethylene, larger than the surface was laid across the entire modular lining table (Fig. 8).

A 14' x 17' piece of Soft Faced Monomesh was custom ordered from SCAPA, with the warp or machine direction threads running vertically, to insure the fabric would hang flat naturally, uncurling from top to bottom. The fabric was unrolled onto the prepared modular table, soft side up, and rolls of Beva® film were manually heatset onto the fabric, butting the adhesive together to create a continuous film. The Monomesh fabric, due to its inherent stiffness and open weave, created an overall flat surface, ideal for a uniform vacuum. The rolled mural, suspended upon its standards, was positioned at the edge of the table, and the painting was easily unrolled onto the prepared lining fabric of soft faced Monomesh.

After diagonal measurements and squaring the mural upon the fabric, the release sheets were removed from the adhesive. A vacuum envelope was created, with Dartek nylon film as the top sheet, by sealing all joins of polyethylene and Dartek with an auto finishers heat-resistant masking tape, called Tuck Tape #139. The lining was heat-activated in two sections at a vacuum of 1" mercury. First the top half, then the envelope, was swiveled around, and the bottom half was heatset with the aid of space blankets which quickly brought the layers to temperature. This was monitored with paper thermometers, activated at 65 C. They were strategically positioned across the face of the mural, beneath the Dartek, and circled on top with marker for better visibility.

The lining results were excellent, and no weave interference was detectable. The outside margins were now trimmed with scissors to an even border of 2 1/2" all around the perimeter of the mural, and heat-sealed to prevent unraveling with a Vulcan Hot Edge Sealer tool borrowed from SCAPA. Perimeter holes were burnt through with a soldering iron at approximate 4" intervals, trimmed with a scalpel and set with brass grommets to finish (Fig. 9).

Small losses from screw holes and old perimeter repairs were filled and textured as necessary with Liquitex acrylic paste, and toned with Liquitex acrylic paint. Final retouch was completed with combinations of polyvinyl acetate AYAB, powdered pigments, and Maimeri Restauro colors. Inpaint was sealed locally with Soluvar varnish. The overall surface was dusted with a tack cloth and brushed with a Soluvar matte varnish to finish. The mural was rerolled with interleaves of felt and glassine as before, and transported to the college for three months' storage until their winter break, when reinstallation of the mural could be performed.

The only available space on an auditorium wall required building a wall to cover a sculptural frieze. The college maintenance department constructed the wall with two layers of 4 x 8 x 3/4" plasterboard, nailed to a 2 x 4 sub-frame. A smooth finish was created with tape and spackle. The rolled mural was positioned on its standards beneath the wall and another 2" diameter pipe was positioned atop the standards over the mural. The top edge of the mural was tied to the pipe with cords run through the grommets approximately every two feet. Block and tackle was secured to two hoist arms atop two towers of scaffolding, and to the ends of the pipe attached to the mural. The mural was unrolled as it was lifted into position, hanging from the pipe (Fig. 10). Measurements were taken to square the painting, and the top edge was secured with flathead Phillip's screws with electric drivers, working outwards from the center.

The mural expectedly developed a curl from being rolled (Fig. 11). To flatten the surface, the pipe which had been tied to the top was retied to the bottom, creating an even downward weight. The center of the mural hung off the wall about 1/2". Manual smoothing failed to bring the mural into contact, so the sonotube was lifted and also rolled down the surface. When this failed to resolve the variance, it was determined that the wall may have been concave. Visually the mural appeared flat with no surface distortions and therefore we decided there was no cause for further concern. The remaining edges were secured with screws, and the college maintenance crew were left with the task of framing the edges (Fig. 12).

This installation was accomplished with relative ease in five hours. Two of these hours were spent waiting for the carpenters to locate and raise the scaffolding a section higher. This final photo was taken in June, 1993, two years after the installation. A simple perimeter frame finishes the edges (Fig. 13). There are no visible surface irregularities and the treatment remains a success (Fig. 14).

I highly recommend Soft Faced Monomesh as a lining support for oversized paintings due to the following advantages:

Available width - 390" (32.5'); Flexibility - Easily rolled for transit or storage;
Stiffness - Semi-rigid; capable of combatting the memory of tears and cupping;
Permeability - As a woven fabric, it serves as an air conduit, and simplifies reversing adhesives with direct application of solvents through the reverse;
Soft Face - Fuzzy mark-free surface, excellent for cling or nap bond applications
Materials - Polyester and acrylic are chemically inert and have resistance to changes in temperature, relative humidity, moisture absorption, rot, microbiol attack and organic solvents
High Heat Tolerance - Maximum safe operating temperature - 285 F (acrylic) / 300 F (polyester)
Y-Pin Seam - Angled canvasses and equipment, cycloramas, etc.
Strength - Capable of carrying heavy load
Ease of cutting - Edges heatseal.

Obviously other adhesive systems and numerous installation techniques can be employed with this fabric. It, or another style of monofilament fabric, could be used as a lining fabric, and then strip-lined and stretched onto an auxiliary support. In 1988 Toronto conservator Diane Falvey (who had worked with us during our 2-year lining support research project), used the Soft Faced Monomesh in a laminate with Terytex® as a lining support with an acrylic emulsion adhesive for a 4' x 12' stretched painting. We once used another style of Monomesh, as an air conduit, to increase the size of our negative pressure cold table, which facilitated the lining of a 5'x 13' painting, with an acrylic emulsion adhesive onto Terytex®. Another style of Monomesh was used as a surface fabric on a suction table by the Department of Conservation at the Royal Museum of Fine Arts in Copenhagen, and the Department of Conservation at the National Museum in Brede, Lyngby, Denmark. Numerous other conservation applications may include supporting the washing, drying or hanging of oversized paper and textiles such as carpets or tapestries.
This unusual fabric opens the possibility of saving many marouflage murals, allowing them to be lined, rolled for storage or transportation, and installed or removed with relative ease. Perhaps it will create avenues for the first traveling exhibition of WPA murals.
In closing, I wish to thank my partners, Margaret and John Sutton who were equally a part of this project.