|With its sheer versatility, usefulness and capacity for producing incredible works of art, urushi is certainly has many virtues. However, among these many virtues, it has one significant flaw. Urushi is the sap from a tree closely related to poison ivy, poison oak and poison sumac. Knowing this relationship, it comes as no surprise that although cured lacquerware is completely safe to handle, the lacquer tree and uncured urushi can exhibit the same toxicity associated with its better known relatives—itchy rashes, inflammation and occasionally blistering.
In fact, urushiol, the very chemical that causes this reaction in all these plants, is named after urushi itself. In modern medicine, this affliction of rashes and inflammation caused by any of these plants is called urushiol induced contact dermatitis. Because of this toxicity, urushi must be used with care, avoiding contact with skin and working in a well ventilated space.
Although urushiol toxicity is the main drawback of the use of lacquer, without it, it simply would not be lacquer. It is this very urushiol content in lacquer that oxidizes and polymerizes to create the beautiful and durable surface unique to urushi. It also must be noted that urushi, once fully cured, generally loses its ability to cause a reaction and only very rarely causes rashes in people who are particularly sensitive to the chemical.
Furthermore, the inflammation caused by urushi is considered an allergic dermatitis and with any allergy, there is a possibility of immunity, both innate and acquired. After extensive use, most lacquer artists will develop a partial or complete immunity to these effects, and can use it with greater ease although care must still be taken to prevent giving the rash to others through contact.
For you as an admirer of lacquerware, however, there is very little to worry about. Once urushi is fully cured, the chance of causing a rash is exceedingly small, and even that chance diminishes over time. However, if in the rare occasion a rash does develop from contact with cured urushi, do not give up hope. A thorough but gentle wiping of the lacquer object with alcohol and mineral spirits followed by a thorough washing with a mild detergent and water should help mediate the problem. If the problem persists, it may be necessary to leave the object alone for a period of time to allow the uncured urushiol to fully oxidize.