Materials & Techniques

Granulation

Of all the techniques employed by the ancient goldsmith, granulation has proved the most difficult to reproduce. Even today, with sophisticated magnification devices, precisely controlled temperatures, and other superior technology, rarely is granulation done with the skill that was achieved in ancient times. The Etruscans in particular were masters of the art of granulation, as can be seen on many pieces in the collection.

In the granulation technique, small globules of gold were soldered to a metal sheet to create decorative patterns, or massed to form a matte surface. Granules as small as 0.14 millimeters (found on Etruscan work) were manufactured in one of several ways. Molten metal could be poured into water or onto a piece of charcoal, or small cuttings of gold could be placed on charcoal and heated just to the melting point.

How ancient goldsmiths attached the granules to the sheet-metal surface is still being studied. It is now generally assumed that the granules were soldered into place by colloid hard soldering. A paste of copper salts and an animal or vegetable glue adhered the granules in place; then the piece was heated to the proper temperature. It is also possible that a transfer method was used. The granules could have been laid out on a support engraved with the design, picked up with an adhesive-coated flexible material such as paper or leather, and transferred to the sheet-gold support.

Excerpt from

Barbara Deppert-Lippitz, with contributions from Anne R. Bromberg and John Dennis, Ancient Gold Jewelry at the Dallas Museum of Art (Dallas: Dallas Museum of Art in association with the University of Washington Press, 1996), 26-27.