Aluminum Differential Cover Thermal Results

Blacklane wrote:

fj12ryder wrote:
Yeah, painting the cover was a bad idea, why use something to help dissipate heat and then use paint to help insulate it?

Actually, painting the surface black improved the thermal performance.

The layer of paint has negligible insulating properties, however the black coating greatly improves the thermal radiation away from the aluminum. This was proven in 1804 using a Leslie cube filled with hot water. The 4 sides of the cube were painted with different coatings, including copper and aluminum, but the black side radiated the most heat. The experiment is often repeated in grade-school science classes using different materials with similar results.

In general this is true, but you painted a rough aluminum housing with lots of surface area to radiate heat and now you have a nice smooth surface that in addition has another layer for the heat to penetrate. That's why most of these aluminum housings are not painted.