A wood panel is a veneer plywood-based support medium reinforced with squared timber and used in all types of painting, including oil. In pencil sketches, watercolors, nihonga, and other formats that use paper for their support media, stretching damp paper and then placing it over a panel makes the surface smooth, strong, and stable, eliminating bumps and waves to facilitate the artistic process—even in high-moisture painting applications. Artists can also use panels as support media for photography exhibits and similar displays to make the work stand out and improve overall presentation.

The basic wood panel structure comprises a wooden sheet in the front, approximately 2.4 to 4.0 mm thick, reinforced with squared timber that brings the total thickness to anywhere from 18 to 34 mm. The most common sheet type uses lauan, but there are also sheets made from shina (linden), which has smoother grain on its surface. Squared pine or cedar reinforces the panel, lining the edges on the back side and providing extra support with multiple crossbars arranged in a grid pattern to prevent bending and warping. Bigger panels use thicker squared timber and more crossbars. Incidentally, there are also panels that have sheets on both the front side and back side in order to create an even stronger defense against deformation. Wood panels come in a wide variety of specification sizes, from the standard F, P, M-type, and S-type (custom) painting sizes to the A/B paper sizes and various printing paper sizes.

The word “panel” originally referred to a painting on a mobile or portable sheet, as opposed to religious paintings in Western art and other immobile works on the walls of buildings. Mobile, easy-to-transport cloth-based support media like canvas have now entered the artistic market, but these formats do not fall into the “panel” category.

Artists should note that wood panels can negatively affect artwork when placed in long-term storage or similar conditions. The oil content of an oil painting on a wood panel sheet can cause the wood to oxidize, for example, while humidity and the passage of time can produce grime. Before using a wood panel for oil painting, make sure to perform base processing by thoroughly coating the surface with animal glue (niwaka), a water-borne basecoat (animal glue solution [size] + chalk), gesso, or a similar solution. When painting on paper with water-based materials (watercolors, nihonga, etc.), on the other hand, it is a good idea to underlay the paper (new torinoko paper, etc.) by sticking it to the front of a wood panel. Also note that plywood panels made of shina guard against possible oxidation and grime problems more effectively than lauan panels do.

Wood panels are available for purchase at general art supply stores.