Second, in our technical series on painting icons, this article discusses the technique of making joined icon panels from several boards in detail, from wood structure to joinery. Although this article applies specifically to icon boards, it has a wider application to making solid wood panels for painting.
Depending upon their size, small icon boards are usually made from a single piece of wood. However, many ancient icons were written on large panels made from joined boards. Such boards were manufactured from a single section of wood by splitting a log, taking into account the position of the natural wood fibers. After splitting, several rectangular sections were obtained and further worked by hewing into shape. Icon boards prepared thus very rarely warped and practically did not develop cracks.
The wood saw first appeared in Russia in approximately the 10th century, but it was apparently used only for the first several centuries for transverse sawing. The longitudinal sawing of wood became common much later, which written sources mention from the 17th century onward.
Since the 11th and 12th centuries, icons of significant sizes began appearing in Russia. For example, the icon of Peter and Paul painted for Sofias Cathedral in Novgorod has a dimension of 236 х 147 centimeters. This size of board fashioned into shape from a single piece of wood would have been impossible; therefore, such monumental icon panels consisted of several smaller-sized boards cemented together.
Fig. 1 (Above) Incorrect arrangement: The wood structure of these boards is aligned identically so that deformation will be in the same direction, making warping more pronounced.
Fig. 2 (Below) Incorrect arrangement: The wood structure of two adjacent boards is aligned identically so that deformation will be in the same direction, making warping more pronounced in this direction.
The structure of the wood should be considered when gluing together several boards to take into account its possible deformation. One should not join boards with an identical wood structure since this will intensify the glued assembly's warping. A slight deformation of the central board’s edges will become more pronounced at the perimeter of the entire assembly, even if the outside boards are deformed in the same direction as the central board. Figures 1 and 2 indicate the direction of warping an incorrectly glued board assembly. To decrease the likelihood of warping, boards should be placed in such a way in the glued assembly that the directions of the deformation of adjacent boards are opposing (Fig. 3).
Fig. 3 (Above) Correct arrangement: The wood structure of adjacent boards is aligned differently so that deformation is in different directions, reducing warping.
Fig. 4 (Below) Using square bars makes this arrangement the least likely to warp.
An arrangement even less likely to warp is achieved by replacing the central board of the glued assembly with 2 or 3 square bars (Fig. 4). This gluing method has only relatively recently been adopted for icon panels; however, boards glued in this manner practically do not warp. The reason for this is because warping of the entire assembly usually occurs due to the deformation of the central board and by the lateral boards being displaced more by the principle of the lever (Fig. 5). If the center section of the board assembly consists of several square bars, which in no way warp, the entire assembly is deformed only due to the outside boards, whose deformation, in this case, will not be exaggerated.
Fig. 5 Deformation in joined boards becomes exaggerated due to the lever principle.
The lateral surfaces of the cemented boards must fit together snugly. For stronger assemblies, a tongue and grove or dowels may be used at joints (Fig. 6). However, this type of joint is not frequently found in ancient and contemporary icons. What is more frequently encountered is a lap joint, shown in Fig. 7.
Fig. 6 (Above) Tongue and groove joint.
Fig. 7 (Below) Lap joint.
Boards are cemented together with the aid of joiners glue. Polyvinyl acetate (PVA) glue, or white glue commonly found in hardware stores, gives good results. It is not advisable to use epoxy glues since they contain substances capable of causing failure in the ground. After putting glue in the joints, the board assembly is pressed together in a clamp (Fig. 8) and remains in this position while the glue completely dries. The edges of the boards are fixed in a “C” channel that prevents their displacement. In antiquity, cemented boards were gathered together with wooden wedges.
Fig. 8 Press to glue boards together with a detail of a “C” channel to prevent boards from becoming misaligned.
Particular attention should be given to knots. If knots are present in the wood, it is necessary to remove them (usually with the aid of drilling), after which a small piece of wood from the same tree species is pressed into the cavity, or the cavity is filled with a mixture of sawdust and joiners glue. Knots should never be left in the board since they are denser than the remaining wood and, therefore, do not shrink according to their structure. Since the cavity in the board where the knot is located is in the form of a cone. In contrast, the board dries the knot is pushed out in the direction of the wider end of the cone (Fig. 9). If this side is turned to the side of the front surface of the icon, the ejection of the knot will occur through the ground, which is impossible to repair without destroying the ground surface. Furthermore, the icon board usually dries for a specific time after completing the icon painting; therefore, the remaining knot can make itself known several months (or even later) after writing the icon, spoiling (sometimes forever) the entire work.
Fig. 9 Knots should permanently be removed from boards because they will be ejected as the board dries.
After gluing, the board assembly is cut to the dimensions and shape of the required icon panel, keys may be installed, and the front surface of the board is carved to shape an ark (kovcheg ковчег), after which it is prepared for painting. This will be covered in the following articles in this series.