Ian, G3SEK wrote:
"Also beware of the nickel-based EM shielding paint which is magnetic
and "meant to be lossy".

Good idea.

Does nickel-based paint make an aircraft disappear from the radar? I`m
kidding but there are such paints and they should probably be avoided
too.

I advised the questioner to SEARCH on "spray-on zinc". Doing that
myself, there were many responses so the product must be popular. I saw
offers of combined zinc and aluminum.

Due to their places at the top of the electromotive series, aluminum and
magnesium may be considered more protective of steel than zinc. Metals
at the top of the series tend to pass into ionic form more readily than
metals lower in the series. The ions are formed by loss of electrons.

If aluminum is thought to give better protection, it`s probably not
surprising to see it offered in a protective coating. Aluminum is one of
the most abundant substances on earth, so its cost is likely reasonable
even though refining is not as cheap as some other metals.

I did not study the responses very long, but I don`t remember any
mention of nickel. If Ian says it is on the market, I believe it is
available and is to be avoided.

Best regards, Richard Harrison, KB5WZI