Goldbeating

Goldbeating is the process of hammering gold into an extremely thin unbroken sheet for use in gilding.

5,000 years ago, Egyptian artisans recognized the extraordinary durability and malleability of gold and became the first goldbeaters and gilders. They pounded gold using a round stone to create the thinnest leaf possible. Except for the introduction of a cast iron hammer and a few other innovations, the tools and techniques have remained virtually unchanged for thousands of years.

The karat and color of gold leaf varies depending on the amount of silver or copper added to the gold. Most goldbeaters make 23 karat leaf. The gold and its alloy are put in a crucible and melted in a furnace. The liquid gold is poured into a mold to cast it into a bar. The bar of gold is put through a rolling mill repeatedly. Each time through the mill, the rollers are adjusted closer and closer to each other, to make the gold thinner and thinner. The bar is rolled to a thickness of 25 µm (1/1000 of an inch).

After rolling, the ribbon of gold is cut into one-inch squares. The first step in the beating process is called the cutch. The cutch is made up of approximately 150 skins. In the early days of the trade, ox intestine membrane (Goldbeater's skin) was used to interleave the gold as it was beaten. Today other materials, such as Mylar, are used. Using wooden pincers, the preparer picks up each square of gold and places it in the center of each skin. When the cutch is filled with the small gold squares, it is wrapped in several bands of parchment which serve to hold the packet together during the beating. Parchment is still the best material known to withstand the hours of repeated hammer blows needed to beat the gold.

The gold is beaten on a large, heavy block of marble or granite. These stone blocks were sometimes placed on top of a tree trunk set deep into the ground. This created greater resiliency for the hammer. Beating of the cutch by hand takes about one hour using a fifteen pound hammer. The goldbeater instinctively follows a pattern and sets up a rhythm, striking the packet with up to seventy strokes a minute. The packet is rotated and turned over to ensure that the gold inside expands evenly in all directions. The original small squares of gold are beaten until they have expanded to the outer edges of the four inch square cutch. The gold is taken out of the cutch and each piece is cut into four pieces with a knife. Using the pincers, these squares of gold are put into a second packet called the shoder, which has approximately 1,500 skins. The shoder is beaten for about three hours until the gold has expanded to a five inch square.

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Wikipedia