From archives and other sources we know that The Night Watch has been lined at least four times. Lining a painting basically means glueing a support canvas against the original canvas on which it has been painted. The first lining of The Night Watch took place before 1851, probably during the eighteenth century. Other than the fact that it was executed, we know nothing about the method or the materials that were used for this treatment. However, we can surmise that the base of the glue mixture was an animal glue.

Wax and resin

The second lining – or more correctly re-lining – is an important moment in the conservation history of The Night Watch; this was the first time the painting was lined with a mixture of wax and resin. This lining method had been invented by Nicolaas Hopman (1794–1870) shortly before and was applied by him to The Night Watch in 1851. The treatment was carried out in two steps. First the reverse of the painting – stripped of the old eighteenth-century lining canvas and glue – was covered with a warm, molten mixture of beeswax and resin. This was ironed in, also from the reverse, with warm hand-held irons to allow the wax-resin mixture to melt through the entire paint structure. In this way, loose or flaking paint on the front of the painting was fixated. In the second step of this treatment, a lining canvas was placed against the original canvas, after which the molten wax-resin mixture was again applied to the reverse. A second round of ironing made sure that the two canvasses would stick together well.

Popular

This new way of lining became very popular in the Netherlands, and later also in other countries. It supposedly protected old master paintings better against our humid climate than the traditional lining method. In 1945 The Night Watch was relined again, because the relining applied by Hopman no longer sufficed. Christiaan Jenner (1896–1977) carried out this second wax-resin relining – the third (re)lining in total – in much the same manner as Hopman had done almost 100 years earlier. The main differences were that Jenner's lining canvas was thicker and that he adjusted the proportion of the wax and resin in his mixture. The third and last wax-resin relining, the one we still find on the painting today, was applied in 1975 under the direction of Luitsen Kuiper (1936–1989). The reason for its application was the infamous knife attack on 14 September 1975. The execution of this relining is documented step by step in the Dutch documentary 'De Nachtwacht onder ’t mes'.