IN RECENT YEARS, conservators at the Freer Gallery have been studying its collection of Islamic metalwork inside and out. The main thing they've discovered is that its bronzes are brass.

The Freer's show, "Islamic Metalwork," gleams despite this revelation. It combines the technical with the aesthetic, and at times the catalogue reads like a chemistry book.

Bowls, canteens, knives, ewers, candlesticks and incense burners, Islamic metalwork is the ultimate in decorative arts, every inch covered in beautiful scrollwork like illuminated manuscripts.

Solving the mysteries of these 38 objects that span a thousand years has been made more difficult for lack of autographs. Few of them were signed.

Their inscriptions, like this one on a mid- 13th century Syrian canteen, are breathless run-on sentences: "Eternal glory and secure life and increasing good luck and enduring power and overwhelming safety and perpetuity to the owner." With fantastic inscribed figures in Christian and Islamic themes, the canteen may have been made for a crusader who wanted a souvenir flask.

From Iran or Afganistan, a decorative pen box is unusual in that it has the name of the artist and patron and date -- it was made by Shazi for a grand vizier in 1210 A.D. On the pen box, engraved and inlaid in silver and copper, scrolling vines become letters, and letters are topped with human heads.

Another magnificent piece of work is a candlestick made in 12th-century Afghanistan. A foot and a half wide, and almost as tall, the base was formed entirely from a single sheet of hammered brass.

"It's a tour de force," says Freer conservator Paul Jett. "It defies belief." In the course of his study, Jett found it had been cast, spun, and hammered thousands of times.

"The more information you have of this sort," says Jett, "the better chance you have of determining what's real and what's not, the provenance of objects. It takes a huge body of knowledge about a great deal of objects to judge a single object that comes along."

For example, says Jett, "If a candlestick like this showed up on our doorstep and it was cast in bronze, that would be very suspicious."