What is gold leaf? How do they make gold leaf? --- Ian, Cary, NC
Marshall Brain Answered:
Gold leaf is gold that has been hammered very, very thin. You start with a bar of gold. You roll the bar repeatedly until it is 1/1,000 of an inch thick. And then you put the gold between pieces of animal skin or parchment to keep it from sticking and you keep hammering it. Gold is unique in that, if you keep hammering it, you get it to where it is just a few atoms thick. According to this page which describes the process, you can get it down to a thickness of 1/250,000 of an inch after about a day of hammering.
The dome of the capital building in Atlanta, Georgia is covered in gold leaf. It's a huge dome, but just 20 ounces of gold was enough to cover it. When you consider that 20 ounces of gold would fit into something about the size of a tennis ball, you can see how much the gold spreads out.
You can see how thin gold leaf gets in this video:
Here's how to apply gold leaf: