The assembly systems we have just described were used to join cross-members. Two further systems were employed to attach these members to the panel, one using wooden dowels, the other iron nails. Both techniques were in use in the 12th century to fix cross-bars or carvings to the support, although nails were most common. Iron nails are found from the 12th to the 16th century in supports from the Spanish, French and Italian schools;1Editors’ note: Uzielli 1998: 122–5; Dardes and Rothe 1998. wooden dowels occur in those from Portugal, Spain, and Germany. Out of a total of 37 panels, 31 are nailed and only six fastened with dowels.

A contract awarded to the painter Luis Borrassà on 21 February 1403 requires him to provide the altarpiece for Santa Maria de Manlleu with adequate cross-members and to ensure it is ‘well nailed’.2Madurell Marimon 1950: 151. Another contract, which Borrassà received on 29 August 1404, to paint an altarpiece for the church of the Convent of the Poor Clares in Villafranca del Panadés, likewise emphasised the need for ‘good wood, adequately provided with cross-members and well nailed’. Similar instructions are found for the main altarpiece of the parish church of Sant Marti de Palafrugell (Girona province)3Madurell Marimon 1950: 156–213. and also that for Sant Vincenç de Montferrer, painted by Ramón Gonsalbo (Raimundo Gonzalvo) (ca. 1428–1474/84), according to a contract granted in Seo de Urgel on 4 December 1458.4Madurell Marimon 1946. Wall panels made in Dijon in 1395–96 were glued together and then reinforced with nails (clouure), to which end Pierrenot Barbisez supplied ‘13,500 small nails and 400 large nails’.5Monget 1898: 275. Similarly, ‘300 flat-head nails [cloux à clavin] to nail the canvases, so that these might be painted on more easily, will be supplied to Malwel [Malouel] for several paintings and altarpieces that he is to paint’.6Monget 1898: 313.Editors’ note: on materials supplied to artists working for the Burgundian court from c. 1375 to 1419, see also Nash 2010.

Nails were, therefore, an important element in the construction of the panel. The importance of woodworking in the Middle Ages led to advances in nail-making, increased the number of different types and spread their use very widely. Nails were used in the manufacture of all sorts of objects in the Middle Ages and through to the 15th century. We simply have to look at the locks, ironware, saddles, furniture, costumes, armour or book-bindings produced in this period to understand the care and prestige that went into shaping the heads of these nails, which frequently served a decorative purpose.

Nails were used to fasten cross-members, reinforcements and frames together and to the support. They were driven through the front of the panel with the result that their heads can be detected beneath the picture surface (Fig. 101) or in the decorative elements of the frame (Fig. 118). The points were clinched over on the back (Figs 68 and 102). It is reasonable to assume that the form of these nails varied according to their specific use. The cross-member of the central panel of Antonio Ronzen’s Altarpiece of the Passion was attached to the support by a kind of iron peg (Fig. 131) held in place by iron cross-pieces. An approximation of this system is shown in Figure 128.

The thinner cross-bars used in Spanish panels were fixed using four-sided forged nails – these are thin and display a clinched point on the back (Fig. 129). Nailheads were waxed to shield the metal from the ground on the front of the panel. The cross-bar nails used in Italy closely resemble those in Spain, and the method of assembly was also similar. We examined the cross-members of Florentine panels from the 14th and 15th centuries: the predella of St Francis of Assisi Receiving the Stigmata by the School of Giotto; Fra Angelico’s (ca. 1390/95–1455) Martyrdom of St Cosmas and St Damian; and Fra Filippo Lippi’s (ca. 1406–1469) The Virgin and Child between Two Saints.7Paris (Musée du Louvre) (Painting index, nos. 572, 576 and 604). Some of these members have been lost, but the nails, which remained in the wood, are still visible from both the front and the back of the panels (Figs 100 and 101).

Other types of nail – lighter than the pegs in Antonio Ronzen’s altarpiece – were used to attach cross-members in the 14th- and 15th-century southern French schools, especially those of Provence (Nice, Avignon), as well as in Italy and Spain. The predella of the Great Altarpiece of St John the Baptist in the Masséna Museum in Nice, attributed to Jacques Durandi (ca. 1410–1469), is one example.8Painting index, no. 506. There are numerous examples in Spain: the Catalan, Aragonese and Castilian schools of the 13th to the 16th century include a large number of panels with nailheads visible from the front, the clinched points of which hold the reinforcing members in place.

Dowels must have been a much more common fixing method. They appear chiefly in Portugal and Germany, where they were used to fix cross-members to panels, particularly in the Viseu and Rhine regions. Dowels were not always used on their own but in conjunction with iron nails, which therefore played a complementary role in reinforcing these assemblies. Vasco Fernandez’ Creation of the Animals9Lamego (Painting index, no. 312). was reinforced with a cross-member in the upper part of the panel. The wood at this location has been smoothed and bears the marks of four holes10See Fig. 88, and detail Fig. 132. in which traces of dowels can still be detected.

There is a very interesting panel from the 15th-century Rhine School showing Christ and the Apostles, attributed to Hans Wechtlin (ca. 1480–after 1526).11Colmar (Painting index, no. 943). The cross-members were originally fixed to the surface of the support and were only recessed at the ends. Four wooden dowels, driven in from the front, also held them in place. The panel likewise shows traces of other dowel holes on the top and bottom edges. Different types of dowel were therefore used both to construct and to reinforce this support from the Upper Rhine region, which shows no trace, incidentally, of any iron fittings. The same applies to Gaspard Isenmann’s Passion Altarpiece.12Colmar (Painting index, nos. 325–327). In its original configuration, the panels making up this ensemble were held together by cross-members kept in place by wooden dowels driven in from the front. The panels have been separated and the cross-members lost, but dowels are still visible below the paint layer in some of them, most notably the panels showing Christ’s Entry into Jerusalem, The Last Supper, The Lamentation, The Entombment, The Agony in the Garden and The Betrayal of Christ.