A black colored block helps to dissipate heat more evenly. But it also depends on what you're painting it with, as in what type of paint. They make paints that are available for radiators that don't inhibit the Heat transfer: Eastwood Company
The short answer though is that the effect would be very minimal, probably not measurable against a control. But it sure would look nice.
Uh, in total darkness aren't all colors invisible?
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Main Entry: co de pen dence - see codependency
co de pen den cy
Pronunciation: \kō-di-ˈpen-dən(t)-sē\
Function: noun
Date: 1979
: a psychological condition or a relationship in which a person is controlled or manipulated by another who is affected with a pathological condition (as an addiction to alcohol or heroin) ; broadly : dependence on the needs of or control by another
Depends what they look like, I suppose. I like to joke that I'm glad I'm nearsighted rather than farsighted because I can always tell who I'm in bed with. My being a massive geek adds some irony to this as I'm hardly fighting women off.
__________________
Main Entry: co de pen dence - see codependency
co de pen den cy
Pronunciation: \kō-di-ˈpen-dən(t)-sē\
Function: noun
Date: 1979
: a psychological condition or a relationship in which a person is controlled or manipulated by another who is affected with a pathological condition (as an addiction to alcohol or heroin) ; broadly : dependence on the needs of or control by another