Tole refers to decorated tin and iron wares from 1700-1900; however, most people also use the term to refer to various painted metalware from the late 19th to mid 20th Century. In traditional Tole, oil paint is the medium used for the pictures; while japan-paint was the background. The method of painting is refered to as 'one stroke painting'. The designs are composed of fruit, flowers, birds, scrolls, and leaves. Gilding, (gold), was used mainly from the 1790's-1870's, but not used much these days.
Japan-paint is a varnish-like paint that when applied to metal and kiln dried, resembles an Oriental black laquer finish. It has a tendency to scratch easily. Most country toleware was not varnished, but items like tea trays usually were to protect the painted surfaces. (pg. 207, 'The History & Folklore of American Country Tinware, 1700-1900, by Margaret Coffin, 1968 edit.).
Tole painting was done on lacquered paper mache items like tea trays; on furniture, and on metal, (japanned tin) trays, silent butlers, document boxes, spice sets, coal skuttles, etc.
Early tin/tole ware items like trays had rolled over edges; soddered corners, and are lighter in weight than late 19th-20th century items that are often made of sheet metal. Newer trays will usually be made from one solid piece of metal and are heavier than the tin trays. If the tray has a straight cut edge, it likely dates from the 1950's to present.
The colors on antique toleware items are very bright, (unless dirty); modern decorators dull the colors in an attempt to copy the old.
To care for tole the author of the above referenced book recommends a mild cleaning with soap & water; then apply a thin coat of varnish or wax. If it needs restoration, find a skilled artist. (pg. 210).