Italian researchers say ancient craftsmen created metal-coating techniques 2,000 years ago that have never been matched, even today.

Writing in the American Chemical Society's journal Account of Chemical Research, scientists in Rome say understanding these sophisticated metal-plating techniques from ancient times could help preserve priceless artistic and other treasures from the past.

While scientists have made good progress in understanding the chemistry of many ancient artistic and other artifacts, Gabriel Maria Ingo and his colleagues said, little is known about how gilders in the Dark Ages and other periods applied lustrous, impressively uniform films of gold or silver to intricate objects.

Using the newest analytical techniques to uncover the ancients' artistic secrets, the researchers discovered gold- and silversmiths 2,000 years ago developed a variety of techniques, including using mercury like a glue to apply thin films of metals to statues and other objects.

The method used to apply real gold and silver was also sometimes used fraudulently, they said, to make cheap metal statues look like solid gold or silver.

The findings confirm "the high level of competence reached by the artists and craftsmen of these ancient periods who produced objects of an artistic quality that could not be bettered in ancient times and has not yet been reached in modern ones," the researchers said.