The process of japanning upon light iron work, like the frames of oil and gasoline stoves, is simple, but requires an oven constructed on purpose for this kind of work, where any amount of it is to be done. Japan varnish is first applied, and the articles then placed in an oven heated to a temperature of from 250 to 300 degrees. The articles remain in the oven from two to four or more hours, according to the color desired, black and brown requiring the longest baking and being the most durable colors. Light colors require a less degree of heat and not so long time, but are not so durable. For japanning, the ovens are usually made of brick for safety, and heated by an iron flue or stovepipe passing around the room, the fire being on the outside. Some place a heater in a chamber below the drying room, arranged to let the hot air pass up into the drying room. There should be no communication between the hot air chamber and the open fire that could possibly admit the vapor of the varnish to the fire. Steam at high pressure may be used for heating the oven when convenient, and is safer than a stove.
(2) Japanning is the art of covering bodies by grounds of opaque colors in varnish, which may be afterwards decorated by printing or gilding, or left in a plain state. It is also to be looked upon in another sense, as that of ornamenting coaches, snuffboxes, screens, etc. All surfaces to be japanned must be perfectly clean.