Radiator construction

MopaR&D said
I know for sure painting the tanks won't do anything because those parts aren't intended to shed heat anyway, they are just tanks to hold the coolant. And just an assumption but unless you manage to fully coat all of the fins and tubes through the entire thickness of the core (not easy) I highly doubt it will affect the heat transfer ability. "Radiator" is a misleading name anyway, they don't work off radiation they work off convection. Black vs. white surfaces only affect radiative heat transfer, like from an old-school cast iron stove that sits in the middle of a room. You feel the heat coming off it even if the air isn't moving around.

I was worried about painting my radiator at first, I was looking for special "radiator paint" then I did a common-sense reality check and just used some simple Krylon combo black paint+primer (less coats needed without a separate primer). Could still be a real thing though I don't have evidence to say it's not true.

Actually, you can't shed thermal energy, unless it is radiated through the air or conducted through contact. Thermal radiation is the movement of thermal energy from one mass to another. Convection is the flow of air due to thermal energy and differential temperatures. Heat sink with no fan is a good example of convection cooling. aka, heat rises. Put a fan across the heatsink and it really isn't convection anymore because the fan causes the air flow.

We proved that painting the inside surface of our product's aluminum enclosure matte black reduced the internal temperature up to 8% in a convection environment. That was enough for us to add that cost to manufacturing so the product could exceed its performance ratings with enough margin. I was just curious if they had done any testing. I'm fairly certain the difference is measurable, but whether it is significant enough to add the cost is a different equation.