THE LININIG OF OIL PAINTINGS ON A VACUUM TABLE

 

Algimantas Vaineikis

Lithuanian Art Museum P. Gudynas Restoration Center

Rudninku str. 8,

2001 Vilnius

Lithuania

 

The Baltic Nordic Conference on Conserved and Restored Works of Art 6-9 October 1999, Taliinn, Estonia. The Conservator as Investigator. Tallinn, Conservation Centre Kanut, 2000. P. 163-164.

 

Lining With Isinglass

A heating vacuum table with a perforated plate was used for the lining of paintings with isinglass some years ago. Experiments with canvases of different thickness were carried out gluing them with isinglass. They were fixed with a 3%-12% isinglass solution with honey as a plasticiser. It was noted that the adhesion increased twice as much when using the vacuum. In this case an isinglass solution of less concentration can be used than lining by the usual glue method. Adhesion of canvases while using vacuum lining with 5% isinglass glue with honey was the same as lining by the usual method with 10% isinglass glue. Seeking to avoid glue penetration to the backside, the cloth of the lining must be prepared very thoroughly, the thread thickenings must be levelled and the canvas surface must be equally covered with the cold isinglass jelly. Suction without heating should be used and the moisture should be allowed to evaporate after the suction treatment.

Special attention should be paid to the preparation of the lining canvases. Any thread thickening can leave imprints on the painting. Attempts also were made to consolidate the paint layer on the vacuum table. The paint layer was consolidated but the glue penetrated through the canvas. To avoid deformations of the canvas while consolidating the paint layer the painting must be stretched and smooth.

 

Lining With Copolymer A-45K

In 1997 some experiments on the lining of paintings with the acrylic copolymer A-45K were carried out at the painting conservation department. Comparative research of 15 polymers was carried out at the P. Gudynas Restoration Centre by means of selecting the most suitable museum textiles for lining in 1980. Vinylacetate, butylacrylate and acrylic acid copolymer A-45K met the requirements raised for the best lining glue (J. Senvaitienė et. al., 1981). Experiments were done on canvas strips of different thickness and density. A-45K copolymer 5% solution in acetone was sprayed on the strips fastened to stretcher. All the strips were divided into three parts. The first part was sprayed once, the second one twice and third thrice. Thus, a polymer layer of different thickness formed on the canvas strip's surface. After spraying, the canvas bands were kept for a day and a night in order that the A-45K "cobweb" might settle better. Then the strips were cut to pieces and glued together by pressing with a warm iron. The temperature was increased from 30 to 60C. The canvas pieces were glued in various order, beginning with the unsprayed pieces with the sprayed ones. The bonding strength was checked by tearing off the glued strips by hand and drawing them in opposite directions with a force like that when stretching a canvas on a stretcher.

So the canvas of different roughness were glued together. The bonding of canvas of great roughness was insufficient even when they were pressed together after spraying three times. The bonding of small grained canvases was best of all. The bonding was better when both canvases were sprayed and weaker when only one of them was sprayed. While increasing the temperature the conclusion was made that canvases glue together best at a temperature of 50- 55C. The bonding of canvases sprayed thrice was too strong. The best bonding was when canvases are sprayed twice.

After gluing tests of the canvas strips, five oil paintings painted on linen and one on cotton were lined on a vacuum heating table using resin A-45K 5% solution in acetone.

Special attention should be paid to the preparation of both the artist's and the lining canvas when lining on a vacuum table. Any thread or thread thickening and even small unevenness in the canvas can be imprinted on the paint layer while using a vacuum. The canvas should be very similar to one another in their weaving and graininess. It is unsuitable to line if the texture of the artist's canvas is thinner then that of the lining because the pattern of the lining will press itself on the painting surface. The canvases adhere best when being sprayed twice, when the temperature of a vacuum table is 50-55C and when they are under suction for 20-30 min.

A-45K solution spraying raises difficulties as special premises are necessary. Temperature and moisture are of great importance when the spraying is done in the open air. When the weather is damp, the solution does not spray.

 

Conclusions

One of the positive features of lining on a vacuum table with a perforated plate, using isinglass is that canvases are bonded equally and less glue is used. Paintings are much more elastic and react more evenly to temperature and moisture fluctuations.

After tests and lining five painting with copolymer A-45K, the conclusion can be made that it has features suitable for lining. First, it is very elastic. It can be applied for gluing edges, for partial and full gluing. This lining is simpler and does not destroy the artist's canvas and while preparing for the lining procedure, it does not require sanding the canvas as only disinfection and cleaning are necessary. When spraying the polymer, only the canvas surface is covered with the polymer "cobweb". Acetone evaporates and does not enter the canvas at all. The sprayed canvases can be lined with an iron or on a vacuum heating table. If some needs arise, the painting can be easily relined. A-45K copolymer is suited particularly for thin cloths and cotton and also for church banners with oil painting inserts when the fastening onto a stretcher is impossible. It is not suited for lining thick canvases with large tears or punctures because the lining is too elastic.

In the end we conclude that A-45K copolymer is suited for lining, but not for all pictures.

 

Materials

Copolymer A-45K

Nischnegorodskij Gosudarstvennyj

Universitet im. N.I. Lobachevskogo

pr. Gagarina 23

603600 Noschnij Novgoro,

Russia

 

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