Robert Dossie, Handmaid to the Arts (1844):
By japanning is to be here underftood the art of covering bodies by grounds of opake colours in varnifh i which niay be either afterwards decorated by paintings or gilding, or left in a plain ftate.
Britannica.com:
Japanning, in the decorative arts, process popular in 18th-century Europe for finishing and ornamenting wood, leather, tin, and papier-mâché in imitation of the celebrated lacquerwork of the Japanese. In modern industry, the term refers to the decoration and protection of the surfaces of metal articles with finishes hardened by oven heating.