gold coating vs. gold plating

This is a question for anyone who actually has experience with
metallurgy and/or gold plating techniques. I've heard that it's
possible to actually /coat/ brass just after melting it with molten
gold (as opposed to plating a brass object) to yield a product that
will maintain its gold surface indefinitely. Could a metallurgist
please offer an opinion on this?
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Gold plating involves deposition of pure gold from a solution at near room temperature by applying an electric current.
You asked about dipping brass into a bath of molten gold. For the process you described to work the melting point of the pure gold bath would have to be below the melting point of the brass alloy.
Now, the melting point of pure gold is 1063 C.
Brass is an alloy of copper and zinc. It does not have a single meting point like a pure metal. Instead it has a temperature where it starts to melt (the solidus) and finishes melting (the liquidus). For a yellow brass containing 70% copper and 30% zinc the solidus is 915 C and the liquidus is 955 C. For a red brass containing 85% copper and 15% zinc the solidus is 990 C and the liquidus is 1025 C.
The process you described would not work because the alloy would melt when dunked in the pure gold bath.
However, there is an alloy 80% gold and 20% copper that melts at 910 C, below some brasses. See: =93Industrial gold brazing alloys=94
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I think you have been given a garbled description of the actual process. You can take pure gold plating and heat it up to get the gold to diffuse into the solid brass to produce a better bond.
Pittsburgh Pete
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