Joining the pieces of wood through nail-free woodwork
Sashimono is a traditional Japanese woodwork technique in which two or more pieces of wood are joined without any nails. Through the tenon-mortise (tab-hole) rectangular joint, master craftsmen can precisely align and combine adjacent pieces. The central product of Kawatsura lacquerware is curved items—round trays and the like—that contain a thin piece of wood bent cylindrically on the sides, attached to a separate flat piece comprising the bottom. It takes the discerning eye of the artisan to “read the wood” when choosing the best material, avoiding defects such as knots, while precisely cutting the block that will transform it into a beautiful curved piece of lacquerware. The raw piece of wood is processed into a thin, flat shape, then bent gradually as heat is applied to it, after which it is dried to set the curved form in place. Next, the piece, created through skillful manual techniques, is passed to the next craftsman—the nurishi—who reinforces it further by applying the natural adhesive known as urushi.
Example: Making a curved lacquerware piece
Selecting and cutting the wood
The best kind of wood for sashimono is the Japanese big-leaf magnolia (hoonoki), which is supple and easy to process, and which readily takes the application of urushi. The wood piece is cut to the appropriate length and thickness matching the size of the bowl, tray, etc. to be produced.
The raw wood is cut roughly to size into the dimensions of the sides of the desired piece.
Processing both ends
Both ends of the piece are scraped down thinly using a rounded saw, giving them the same thickness when bent into a ring shape and matched up with each other.
Boiling and bending
The initial wooden piece is immersed in boiling water. When it has reached the desired softness, the wood is removed from the hot water and wrapped or curled around a special log called the koro, which the artisan rolls slowly to bend the wood into the desired shape. The ring-like form must be achieved before the wood dries out completely, at which point a wooden wedge is attached to keep the shape in place. The rounded piece becomes the side element of the final lacquerware piece.
Drying the wood and adding adhesive
After three days or so of drying, the curvature is set permanently. Once the piece is completely dry, the wooden wedge is removed and adhesive applied, with uneven areas “broken in.”
The bent pieces of wood are hung to dry naturally.
Inserting the bottom piece
The piece of wood that will serve as the bottom of the eventual lacquerware item is cut so as to slip precisely inside the frame created by the sides, and is then affixed to the frame with an adhesive.
The edge pieces are beveled and molded to facilitate the subsequent smoother application of urushi in the next step of the production process. Additionally, the surface is polished down to a smooth finish.
The ability to make such flawless shapes, without the use of a single nail, is the result of many years of careful training.