Quote:

The most authentic look, would be to have the tank tin plated.





Gas tanks were and are made of terne sheet, which is cold rolled steel sheet hot dipped in an alloy of lead-tin. Originally it was 80% lead, 20% tin, the recipe for solder. More recently the lead has been replaced with zinc, in a ratio of 50% zinc, 50% tin, according to Wikipedia. But ASTM A308, "Standard Specification for Steel Sheet, Terne (Lead-Tin Alloy) Coated by the Hot-Dip Process" still exists.

It says, "This specification covers sheet steel in coils and cut lengths coated with lead-tin alloy by the hot-dip process. This material is commonly known as terne and is used where ease of solderability and a degree of corrosion resistance are desirable. It is especially suitable where resistance to gasoline is required."

I'll bet Chrysler Corp gas tanks were made of 80% lead-tin in the muscle car days. More recently the Canadian gas tank maker Spectra says they are using Ni-terne sheet, which is steel sheet flash coated with nickel before hot dipping in terne metal, but they don't say what alloy of lead-tin (or zinc) is in the terne metal. I believe most all the new repro tanks available on eBay, Quanta, etc. are made by Spectra.

As far as appearance, the original tanks were bright, bare metal, just like the new repro tanks. But over time, any alloy of lead-tin (or zinc) will darken with exposure to the atmosphere, so a preservative like RPM before installation makes sense to keep the bright bare metal look.

You can help brighten old lead or lead-tin by using a polishing powder wetted with vinegar on, for example, gas filler tubes. But don't do this on spangled galvanized or zinc coated steel - it destroys the spangled appearance making all the spangles the same metal color, rather than different shades of silver/gray. If the galvanized is not spangled, or you don't care about the spangles, this method will uniformly brighten it. Then, of course, it will darken again, if you don't put some kind of preservative on it.

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