You can pay as little as $300 or over $4,000 for a reverse painting on glass. You may have seen them as English pub advertising mirrors, insets in 19thcentury clocks or framed as art.

Among the most charming and expensive are those done in China in the late18th century. But, before thinking you have found a bargain at a country auction a history lesson is in order.

The technique of painting on glass dates back to Italy, in the 13thcentury, tho crude examples have been dated to the fourth century A.D. In these the picture was engraved on the back of a piece of glass through a layer of gold leaf that had been attached to it.

Color was added to the reverse side and a second piece of glass sealed it. By the 17th century, metallic foil was used and reverse painting was being done in Central Europe and Germany's Alsatian and Black forest areas. As the craft developed each country created its own style that helps identifying origins.

Surprisingly many European glass fragments have been preserved dating as early as the third century. Popular subjects were adapted from engravings of paintings and woodcuts. Many of the subjects were created as sets or pairs.

Back painting on glass, as it is also known, used oils or colors mixed with gum. It was Jean Baptiste Glomy a French artist-antiques dealer who created what is known as Verre Eglomise that changed the process. He painted on the underside of glass with out using a metallic background. In the late 18th century the black painted silhouettes of statesmen, royalty and famous personages, with black and gold bands painted as borders were popular.

Collectors look for the many fine examples produced in China from the early to late18th century. History has it that an Italian Jesuit, Father Castiglione, introduced the technique to China around 1715. Canton became the center for reverse glass painting. It became so popular that tourists would seek out the artists and have their portraits painted. By the 19th century it had become a common export to Europe and much of the charm of the early work declined. Popular subjects for the Chinese paintings included Chinese and European men and women either as portraits in involved in various activities. Landscapes and harbor scenes are among the most rare subjects and among the most expensive when found. Many Europeans sent favorite engravings to be copied on glass.

A clue for collectors would be European figures with slightly slanted eyes and Oriental plants. The "look" of reverse glass painting was so popular that in late18th-century England that mezzotints and prints were applied to glass. Famous people and sporting scenes were among the subjects. Many were imported to America and turn up in antique shops and shows today. By the 19th century, German immigrants contributed their touch to American reverse painting.

The technique had developed in central and eastern Europe where religious glass paintings were commonplace. In the mid-nineteenth century reverse glass painting became ado-it-yourself hobby for housewives in England and America, using the same techniques as the late18th century professionals had in England.

With the revival of interest in collecting reverse paintings in the 1970s came reproductions. They can be confused with the late Victorian reverse glass paintings that were gaudy and used bits of tinsel and mother-of-pearl in the background. The most common subject for these reproductions was a house, with a small clock dial inset. Chinese export reverse paintings were also, and still are, being reproduced. Federal clocks and mirrors often had reverse paintings of ships or Mount Vernon in a panel. Since these were broken over the years they were replaced, in the 20th century, with new decal prints. Paint-to-order artists over painted these with detailing or.

Before paying too much, judge the quality and the subject matter. Reverse glass paintings were rarely signed.