Preservation of Paper and Textiles of Historic and Artistic Value

13 Some Techniques of Textile Conservation Including the Use of a Vacuum Hot Table

Downloaded by UNIV LAVAL on April 22, 2018 | https://pubs.acs.org Publication Date: December 17, 1978 | doi: 10.1021/ba-1977-0164.ch013

PAT R E E V E S Conservation Center, Los Angeles County Museum of Art, Los Angeles, Calif. 90036 Textiles, as are many objects of art, are subject to the deteriorative effects of dirt, acidity, light, humidity, and mishandling. The steps by which they are conserved are detailed, including a discussion of the problems inherent in their restoration. The use of the vacuum hot table—a recent technique—is exemplified in the treatment of embroideries and two Civil War flags, and the use of adhesives is discussed in regard to this technique.

O i n c e most of my readers are not professional textile people at home ^ among tabby weaves, compound silks, ikats, and double-cloth, I try to keep my textile terminology simple. I mention some of the problems we face i n working with ancient textiles, some of the answers we have come up with, and the solutions for which w e are still searching. It seems chemists have shown a bit of favoritism to painting, metal, and paper conservators and not to the textile conservator. Those i n textiles do need chemical help, and I hope we can work together more closely in the future. A definition of art conservation has been stated by B e n Johnson, H e a d Conservator at the Los Angeles County Museum of A r t : "Conserva tion can be defined as the application of science to the examination and treatment of objects of art and to the study of the environments in which they are placed. Art restoration is the portion of conservation which deals primarily with the treatment of objects. It should be understood that restoration does not imply an attempt to return the object to its original state but rather to prevent deterioration of the original materials while respecting their integrity ( I ) . " I must point out something which is implied i n this definition: a l l of our work is reversible. A t any time, we can stop a process if it is not 181 Williams; Preservation of Paper and Textiles of Historic and Artistic Value Advances in Chemistry; American Chemical Society: Washington, DC, 1978.


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working, reverse it, and try another way. (Later I give you an example of this.) Also, if a chemist discovers a better way of doing something next year, we can reverse what we have done and use the new formula. Textiles suffer from the same perils as do other objects of art: dirt, acidity, light, humidity, and mishandling. In many ways textiles are inherently more fragile than other objects. The degree of fragility de pends to a great extent upon the fibers from which they are created. Silk deteriorates more rapidly than does wool, cotton, or linen. The dyes with which they are colored and the mordants with which the colors are set can accelerate deterioration. Dirt is abrasive and i n some cases has latent chemical properties which can cause damage. Therefore, it is necessary that textiles be cleaned before they are mended and mounted for display or storage. Normally, the first step i n textile conservation is the examination of the piece to determine the fibers from which it was made and the technique by which it was created. One determines the spin of the yarns, whether Z or S, and the number of wefts and warps per inch. Next, one tests for colorfastness: first with distilled water, then with glycerin and water, and finally with a neutral detergent and water. If the colors run with any of these solutions, obviously the piece cannot be washed, and one tests with dry-cleaning solvents and other chemicals. Before washing, the textile is encased in nylon tulle, well basted with a long running stitch for protection in the necessary handling. It is then soaked in a 25% solution of glycerin and distilled water for a few hours overnight. During the process, dirt is loosened and emulsified and the fibers are relaxed. After thorough rinsing, the textile is then gently bathed i n neutral detergent and distilled water. This process sometimes must be repeated. The final step in cleaning is another thorough rinsing in distilled water and a p H test. When the textile has dried on a padding material, it is transferred to a work board of suitable size. M y work boards are made of Homosote (a form of pulp-board) covered with Contact paper. The nylon tulle is removed, clipping each basting thread and removing it with forceps. W i t h the aid of guide lines and T-squares, the piece is steamed and blocked, which simply means aligning the warps and wefts in the posi tion in which they left the loom originally. After blocking, the decision is made as to the means of support to be provided. If the textile is strong enough to hang freely, it is lined with a suitable washed cotton. The lining must support the textile as well as protect it from dust and contact with the wall. The support is achieved by sewing the textile to the lining vertically (and sometimes horizontally) every few inches. The stitches, of course, are invisible on the face of the textile. In this manner the weight of the textile is dis-

Williams; Preservation of Paper and Textiles of Historic and Artistic Value Advances in Chemistry; American Chemical Society: Washington, DC, 1978.


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Textile Conservation and Vacuum Hot Table

tributed and is not being pulled only from the top. It is hung i n one of two ways: by using Velcro at the top or making a sleeve for a hanging rod. If the textile is not to hang freely, it is then mounted on a strainer which has a washed cotton fabric stretched very tightly over it. The textile is sewn and mended down to this mounting fabric and then enclosed i n a 3-sided Plexiglas box, making sure the Plexiglas does not touch the textile. The back of the strainer is covered with a washed cotton flannel, which allows the textile to "breathe" but still acts as a dust and moisture barrier. Some problems are inherent i n the way the textiles are woven or embellished. That is, one can anticipate the manner i n which they w i l l deteriorate and how they can be protected against themselves. One example of this we find i n large European tapestries. Most of them are made with warps running horizontally, instead of vertically, as i n most other textiles. The warps are heavier and stronger than the wefts, but the tapestry hangs by its finer wefts. After many years of hanging, the wefts begin to break and sag, leaving exposed warps. This kind of inher ent deterioration can be anticipated and measures taken against it. Tapestries should have vertical strips of cotton sewn invisibly to the back of the tapestry, giving support to distribute the weight. The fining also helps i n this manner and is useful i n balancing the tapestry to avoid getting ripples in it. Embellished textiles are those on which the decoration is applied after the fabric has left the loom. The most comomn examples are em broidery and needlepoint. Embroidery almost always is done with a greater tension i n the stitches than i n the textile, resulting i n an uneven surface tension. This means that the unembroidered areas w i l l pucker and crease. E a c h pucker and crease w i l l eventually break the fibers, resulting i n a split i n the fabric. The method I have devised to help pre vent this kind of damage is to pad the unembroidered areas lightly from the back using a washed cotton flannel. Just enough padding is added to eliminate the puckers and creases. Another similar problem often occurs with flags, particularly Ameri can flags. They are made of strips of different colors sewn together. The sewing usually w i l l have more tension than the fabric. In ironing even a new flag, one must watch for ripples between the stitchings. In an old flag, when the fabric between the stitching has stretched and sagged from age, the problem is aggravated. In the past when I have had a textile too fragile to withstand a needle, I have pasted a very light silk lining to it, using Japanese rice paste, which is harmless and easily reversible. This method had the advantage of preserving a piece which was otherwise hopeless, but it


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also had certain disadvantages: it was somewhat stiff and would not always lie flat even though it was dried under weights. Today, instead of the Japanese rice past method, I am using the vacuum hot table (2) with a heat-activated adhesive, which is also harm less and reversible. I am stressing here the use of the vacuum hot table in the treatment of textiles as it is a fairly recent technique for us. The vacuum hot table was designed for painting conservators and used by them in re-lining old paintings. The first published account I know of in the use of this table for textiles is by Sheila L a n d i (3) of the Victoria and Albert Museum in London. Another reference is by Kathryn Scott (4). One recent successful use of the vacuum hot table was i n the treat ment of an American C i v i l W a r flag. The flag was brought to me i n such a tattered and fragile state that I could not even remove it from the brown paper bag which contained it. I transferred the contents of the bag into a nylon-mesh laundry bag. I was able to determine that the fabric was a fine wool and to test the blue and red colors which were found to be fast in water. I soaked the flag (still i n the mesh laundry bag) in a glycerin-water solution for several hours. The solution was very dark and dirty at the end of the soak. The flag was then rinsed, washed, and rinsed, washed again and rinsed. B y the end of the final rinse, the water was clear and the p H neutral. Only after the soaking and washing d i d I remove the flag from the laundry bag and place it on a clean sheet on my table. W h i l e it was still damp, I straightened it out enough to be able to measure it (Figure 1). Because of the many losses i n the flag, it was decided to line it with the same colors—actually, to make a new flag for the fining. A suitable cotton fabric was found and dyed exactly to match the original. The "lining flag" was made to fit precisely under the old flag. The usual procedure would have been to thumb-tack the lining to a frame and spray it with adhesive. Because of the extensive losses i n the old flag, however, large areas of the "lining flag" would be shown, cov ered with unabsorbed adhesive. The solution to this was to take an inexpensive cotton fabric, wash it, thumb-tack it to a frame, and loosely baste the original flag to it, wrong side up. The cotton fabric simply served as a support for the old flag while it was sprayed with the adhe sive (Figure 2). After the adhesive had dried, the basting stitches holding the flag to the cotton backing were removed, and the old flag was placed right side down on the "lining flag." It was adjusted properly and the most fragile areas adhered with the use of a tacking iron. It was then moved to the vacuum hot table and covered with silicon paper, to prevent the adhesive from contacting the table, and a membrane which made pos-



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Figure 1. Flagfirsthid out on the table

Figure 2. Flag and temporary lining being sprayed with adhesive



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sible the vacuum. Sand bags were placed around the edges of the table to ensure a perfect vacuum, and the table was set at 65°C ( 1 5 0 ° F ) . At the conclusion of the treatment, a sleeve was put at the top of the flag and the lining on the wrong side so that it could be hung (Figure 3). The flag done on the hot table was successful only because the old flag was so tattered and stringy that it could be made smooth on the lining. The new flag (which formed the lining) was seamed on the sewing machine with a very low tension. On another Civil War flag we were not so successful. This flag was intact enough that it needed only to be lined with a thin silk. Because it was so nearly intact, however, and the fabric between the seams had stretched and sagged, it could not be made to he flat. We were unaware of the problem since it was possible to iron the flag by hand, leaving a

Figure 3.

Flag at conclusion of treatment


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few ripples but no creases. The vacuum table was not so accommodating. It made every ripple into a sharp crease. It was indeed a mess. W e then put the flag face down on a plain table and applied Picrin, a dry-cleaning solvent which is called a "volatile dry spotter," to the back of the lining which reversed the adhesive. That lining was thus easily removed and discarded. Another lining was cut and hand-sewn to the flag along every seam, adjusting ripples as we went. The torn areas were mended to the lining. A n embroidery with very high tension is not a suitable problem for the vacuum hot table. The vacuum causes the piece to become absolutely flat and w i l l make permanent creases and transform the puckers into creases. This does not apply to all embroideries, however. I have suc cessfully done some on the vacuum hot table. The textiles most successfully treated on the vacuum hot table are those which are smoothest and have the least texture. Highly textured pieces are more difficult. For example, a Peruvian tapestry-woven piece was too fragile to sew so it was treated on the vacuum hot table with a thin silk lining. This worked marvelously for the loose wefts on the back of the textile. O n the surface, however, the loose and raveling wefts were not improved because they had not come i n contact with the ad hesive, the surface wefts being, as it were, the top part of a sandwich composed of weft, warp, weft. In attempting to sew down the loose surface wefts, the fragile and rotten warps broke at the first stitch, which was the sign to stop immediately. The answer was to put the piece back on the vacuum hot table, this time adhering the almost invisible silk to the face of the textile. This was not as pleasing aesthetically as I would have liked, but at least the piece is safe and w i l l last for many years. Otherwise it would have totally disintegrated i n a few years. In another Peruvian piece of similar structure, there was no problem because the warps were strong enough to withstand the sewing down of loose surface wefts which were not held by the adhesive. The adhesive I use is Beva 371-B (5). I find it most satisfactory and have not had reason to try any other. A t the Victoria and Albert Museum a polyvinyl acetate emulsion is used. A t the present time, experiments are being carried out testing various adhesives and their effects on textiles when used on the vacuum table. This is being done by Christine Daulton, working under Joyce Stoner H i l l , at Virginia Commonwealth University i n Richmond. The adhesives she has chosen for her experi ments and testing are: polyvinyl alcohol, polyvinyl acetate, Rhoplex N-850, Beva 677, Beva D-8, and both high and low ethyl hydroxyethylcellulose.


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In conclusion, the use of the vacuum hot table is not the answer to every textile conservation problem. It is one useful tool i n the repertory. E a c h work of art, by definition, is unique. Therefore, each textile must be individually treated, using the method most applicable to the problems. Literature Cited


1. 2. 3. 4. 5.

Anal. Chem. (1972) 44 (1), 25A. "Vacuum Hot Table," Peter Koch, Apparatebau, Hannover, West Germany. IIC Stud. Conserv. (1973) 18 (4). AIC Bull. (1974) 14 (2). Formula for Beva 371B: Elvax Resin Grade 150, 500 g; Ketone N . Resin, 300 g; Celloyn 21, 40 g; toluene, 1000 g.

RECEIVED

January 7, 1977.


Preservation of Paper and Textiles of Historic and Artistic Value

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