Gold filled or gold plate

[blondfellow]

As a follow up from my previous post on this. I was reading the Official Price Guide To Watches tenth edition by Cooksey Shugart and Tom Engle and in there is a paragraph explaining the difference.
The first patent for gold filled cases was given to J. boss on May 3 1859. These were more common than solid gold cases only about 5% of case were solid gold. The process is as follow:
Two bars of gold 12 in x 2 in x 3/4 in were placed on either side of a base metal bar the same size. These bars were soldered together under pressure and high heat. These sandwiches were then put through a roller and under high pressure and heat and rolled to the desired thickness. From this the case were stamped. Gold filled cases were usually 10k or 14k gold and marked 10 year, 15 year, 20year year or 25 year. The number of year denoted their guarentee. This was stopped by the government in 1924. And after that they were marked with 10k or 14 k gold filled or 10 k gold plate.

Rolled gold involved rolling gold into micro thinness and, under extreme pressure, bonding it to each sheet of base metal. The thickness of the gold varied and had a direct bearing on their value.

Gold gilding is electroplated,

So as I see it rolled gold is two thirds solid gold.

[chris mabbott]

I wouldn’t say that they’re 2/3 gold. I suppose if you look at a piece of base metal and two pieces of gold pressed together and say that two of those three parts are gold, you would get 2/3″ but, when you look at the actual layer of gold on a case, and see when the gold layer wears off to reveal the brass base, it is definitely not 2/3 solid gold.

The term solid gold would also imply that pure 100% gold was used. Gold is soft and wears very quickly, this is why it is mixed, as in 10k, 18k and I think in the UK back in the day, they used 21k…. With 24k being 100% pure.
So the actual gold you would end up with from a melted down gold filled case is very small, as it is, in reality, a very fine layer a bit thicker than plating.

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