Seals For The Goetic Presidents? Options

Sorry if this has been asked before, but I didn't see it.

Various copies of the Goetia refer to Mercury as the metal of the Presidents, which is all well and good, until you get to the point with the Spirit when for whatever reason you are supposed to, or want to inscribe its Seal upon the appropriate metal. Copper, Tin, Silver, no problem. But how am I supposed to inscribe on Mercury?

I've been considering brass, as it is also attributed to Mercury, or an alloy with Mercury, but I was wondering if anyone else has another idea/suggestion.

Glad I could help.

One last thing--the phrase "mad as a hatter" comes from the dementia hat makers suffered in the old days. They got it by processing felt in various mercury solutions, among other very toxic things. After a time of inhaling and handling (mercury's absorbed through the skin, too) that stuff, their mind started to go, and it was permanent. They didn't realise it was from the chemicals they were using.

@Flyingmojo: that's interesting! I'll have to try that one out and see how it works.