To better understand the history, and traditional uses, and manufacturing techniques of mechanically
bonded metals we are including the following paragraphs from pages 16 and 17 of “The Handy Book of
Precious Metals” put out by Handy and Harman.

Gold Filled
Gold for the millions: The possession of gold in any of its forms, was, until recently, a rather exclusive
privilege. However, an “accident” in a silversmith’s shop more than 200 years ago set the stage for the
popularization of gold, putting it within the reach of millions. This accident led to the development of
gold filled, which is and overlay of 10karat or better bonded by heat and pressure for reinforcing metal.

The origin of gold filled
The silversmith was Thomas Bolsover, of Sheffield, England, who, while using a copper coin as a shim to
hold a silver knife in a vise, discovered that after several hours of clamping, the copper had fused to the
silver. This mechanical bonding process would later be used to fashion fine heirlooms (using minimal
amounts of silver bonded to less costly metals) which not only exhibited the beauty of a precious metal,
but was also affordable to wide stratum of the population. The technique of mechanical bonding, taking
its name from the place of its discovery, was called the “Old Sheffield Process”, and when the amalgam
was produced with gold or silver, the end product was called “gold filled” or ” silver filled”, respectively.

How gold filled is made
Gold filled is produced by fusing a layer of karat gold to a suitable supporting metal (or alloy), using
equipment that carefully control pressure, heat and time. The bond produced is a permanent one. Next
comes a series of rolling operation, which compress the strip into a sheet. Repeated rolling reduces the
thickness of the material in such a way as to preserve the proportionate thickness of the gold and the
supporting metal. Repeated rolling also serves to densify the gold , so that I becomes harder and more
durable.

Requirements for gold filled
Gold filled products must consist of at least one layer of a minimum of 10 karat gold. The karat gold
layer must represent at least 1/20th of the total metal weight. Rolled gold plate is material consisting of
a layer or plating of 10 karat gold or better, but the proportionate weight of the karat gold may be less
that 1/20th (1/30th, 1/40th or as the case may be).