THE LININIG OF OIL PAINTINGS ON A VACUUM TABLE
Lithuanian Art Museum P. Gudynas Restoration Center
Rudninku str. 8,
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 60°C. 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°- 55°C. 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°-55°C 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.
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
In the end we conclude that A-45K copolymer is suited for lining, but
not for all pictures.
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