Any advice on an absorptive or lossy material for use from LF to VHF?

Would a carbon spray (if there is such a thing) do the job?
How about the antistatic foam material semiconductors and other devices
are
packaged in?
How thick would it have to be?
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It is perhaps somewhat expensive ,especially for larger areas , but
conductive paint would do the trick.

Frank GM0CSZ / KN6WH