If you're interested in Urushi, here's an account from an artist who went to Japan to learn how to work with it - https://garlandmag.com/lacquer-god/

"Essentially a concentrated form of poison ivy, uncured lacquer causes blistering rashes which cause its sufferer almost unbearable itch and many sleepless nights. Building tolerance typically takes up to two years and has students living in constant fear of the very material they eventually hope to use on a daily basis."

Ouch. Rereading my source above (Gladman 2006), they say hyposensitization (desensitization, if I understand correctly) generally doesn't work, but ...

"Lasting natural hyposensitization has been reported, however, among Japanese woodworkers who use lacquer derived from Toxicodendron verniciflua, the Japanese lacquer tree. In a 1991 survey, 81% of craftsmen developed dermatitis from the lacquer but 83% of these reactions resolved with continued exposure."