A lining intervention is carried out when the original canvas support of a painting has lost its support strength (whether by deterioration of the cellulose, large-size lacerations or rips, etc.). The operation consists in applying to the back of the original canvas one or more new canvases. The new or lining canvas is temporarily stretched onto a stretcher frame that is larger than the canvas (temporary stretcher). The entire intervention requires particular attention, ability and know-how; not only to insure good adhesion between the old and the new canvas, but also to guaranty stability and solidity to the work as a whole: the ground preparation, the pictorial film and the final varnish layer.
In order to obtain these results, the lining treatment usually requires pressure and heat which liquefies the adhesive allowing it to penetrate; during the operation hand irons or other types of heat sources are used. If these tools are not used with sufficient caution and rationality it is possible to damage the painting.
Lining methods are generally characterized by the type of adhesive that is used: a glue-paste lining (with the use of a glue-paste adhesive), a wax-resin lining (in general out of use), a lining using synthetic resins (in use beginning the second half of the twentieth century). These latter lining types are identified by the commercial name of their adhesive (Plextol, Beva, etc.)
In a manual lining treatment, the lining canvas (usually linen canvas) is stretched with canvas pliers onto a temporary stretcher frame and fixed with nails or staples. The temporary stretcher and the lining canvas are larger than the painting itself. The stretched lining canvas is then wet and left to dry. This operation is repeated, and is finally sealed with hot glue. In essence, with this procedure, the size is removed and the new canvas is “relaxed” and rendered more inert (a more correct term would be de-sizing). This procedure is necessary during a lining process that employs water-based adhesives (so example in glue-paste linings). Various types of equipment and procedures can be used when the hand lining is judged risky or insufficient to obtain the desired results.
In 1930 at an international conference on painting conservation, a heated worktable – ideal for lining – was introduced. The table – known as the hot table – was made of a large slate slab, heated and maintained to about 50/60°C by means of adjustable heating elements that insured the uniform melting of the adhesive (wax-resin). In 1955, the hot table was improved by combining it with a system of vacuum pressure providing for both complete heating and complete pressure. Today, this is the widely used vacuum hot table.
The most recent and perhaps the most interesting advance in the sector of the use of vacuum pressure – is the technique of pressure lining without the use of heat (“cold lining”).
The conditions of the pictorial film are analyzed prior to applying the protective layer. From this analysis it can be decided if a surface treatment is required. This operation is aimed at aesthetically reducing the surface deformities that may be present due to hard buckling. This intervention can be done using a hand iron, or by means of a suction pump after having treated the pictorial layers.
A lining treatment is always a traumatic intervention for a painting, and therefore, when possible should be avoided. An intervention requiring a consolidation or color fixing does not necessarily imply that a lining must also be carried out. When, for various reasons, a painting has been removed from its stretcher/strainer in order to re-mount it, it is often sufficient to apply a strip lining; that is, the application of perimetrical strips of canvas to the tacking edges of the original painting.
Often, the original stretcher/strainer is neither solid nor stabile enough to support the tensioning of the canvas. In addition, in the case of the stretcher, the tension of the painting can not be easily regulated over time. When this support structure is substituted, a strainer is chosen; that is a support system that can be regulated by “keying out” (tapping wooden keys placed at the angles) or by a system of continuous expansion.
Manfredi Faldi – Claudio Paolini
Estratto da: Artis (Art and Restoration Techniques Interactive Studio), Direzione scientifica: Manfredi Faldi, Claudio Paolini. Cd Rom realizzato da un gruppo di istituti di restauro europei, con il determinante contributo della Commissione Europea nell’ambito del programma d’azione INFO2000.
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