Starting with ‘Protection and preparation of the support (Chapter 11), Marette refers to various protection methods observed on both the front and back of panel paintings and which can be related to the advice of Theophilus and Cennini. Normally considered Italian practice, applying linen to panels was also done by panelmakers of the northern countries, as in a large (2.8 m2) painted fir wood lectern (1250–1300) in Torpo, Norway, in which the joins were glued and covered with canvas prior to the application of size and ground.1Braenne 1982. In Germany canvas was also applied to panels. The Adoration of the Magi by Stefan Lochner (active 1442–1451) in the cathedral of Cologne has two wings and a main panel made of oak wood.2Schultze-Senger 1988. The butt ends of the single planks (2.5 cm thick) have been glued together.3Verougstraete-Marcq and Schoute 1989. The completed panels – on what was to become the inside of the wings and the front of the middle panel – were then completely covered with canvas. A linen interleaf was also identified in the wings of the Altarpiece of the Crucifixion (1390s, installed in 1399) by Melchior Broederlam, an artist from Ypres working for Philip the Bold, Duke of Burgundy, for his Charterhouse of Champmol, Dijon.4Currie 2009. Acccording to the ducal accounts, Jan Maelwael (before 1370–1415), another court painter working at the Charterhouse, also lined his panels and altarpieces with canvas.5Prochno 2002: 334–35 In 1568 Vasari described this method in some detail.6Berger 1901. A rather thick (1.5 mm or more) ground was used, which became somewhat thinner on the outside of the wings. Applying ground and paint on both sides of the wings naturally reduced movement in the wood. The joins, knots and resinous areas of softwood panels were completely covered with strips of canvas. In the 15th century Danish cabinetmakers used the same procedure – joins and knots were covered with pieces of coarse canvas before sizing with strong glue.7Skov and Thomsen 1981.

Simple division between southern and northern Europe has traditionally been drawn between the use of gypsum in the south and chalk in the north for preparation of panels prior to painting. Reality is not quite so simple, though, because gypsum and chalk were occasionally used in the same work.8Goetghebeur 1996; Mercier et al. 2014; Streeton and Kollandsrud 2014. Marette refers to Larbarte, who stated that ‘white chalk helped preserve the freshness of the colours, but could be detrimental to the adhesion and elasticity of the paint layers’. With current knowledge we find this comment somewhat misleading, since most northern panel paintings and altarpieces from the 14th to the end of the 16th century were executed on chalk grounds.9Stols-Witlox 2014. Furthermore, considerable research has been done since the 1960s on the composition, preparation and application of ground layers, as well as practices associated with medieval workshops and the division of labour.10Federspiel 1995; Nadolny 2008; Stols-Witlox 2012.

In Chapter 12, ‘Cloth, fibre and glue’, Marette uses historical texts and contracts to inform the reader. We should like to add that the method of securing joins by applying parchment and gluing vegetable fibres, horse or cow hair transversely to the join, while used mainly in the 15th and 16th centuries, also continued in the first quarter of the 17th century.11Sonnenburg and Preusser 1979. As the use of canvas as a reinforcing material for panels is documented into the 17th century, a premature conclusion regarding this should be avoided before thorough research has been carried out.