Dull, black, heat resistant paints
have been used to help cool engines for ages.

It would be cool (literally) if one could
spray and heat-cure unshielded tubes
and improve their heat-shedding

Is there any indication that such paints,
or some vacuum-tube specific types,
would help keeping tubes cool
by improving heat radiation?

I'd love some factual info, if it exists, or educated guesses,
rather than uninformed blind guesses,
as I am awfully good at doing uninformed blind guesses already! :-)