Few crafts in the world are more revered, or more demanding, than Japanese lacquer. The main ingredient is urushi, the sap of a tree closely related to poison oak. Working with it can be a harrowing experience: itching, rashes, and respiratory problems are commonplace. Traditionally, lacquer-making families have gradually exposed their children to the substance, hoping to build up at least some immunity to its toxicity. Then there’s the actual craft process, which is slow and painstaking in the extreme. Applying liquid urushi to wood or some other substrate, layer after layer, produces a deep, glossy surface; pigments are added in the last few layers. To the uninitiated, the finished results can look like plastic. To those in the know, there is nothing more beautiful.