Don M

Do a search on heat rejection and color of radiators. It will save me a ton of typing trying to explain and you can read it from multiple sources.

The black paint should be flat and should not be layered on too thick, or like you said the insulation effect can take place.

There is also radiator specific paint for this very reason.

Don~

BoostdCTD

Hmm, while I don't disagree that black may be a better heat exchanging color (thermal emissivity?) but I do disagree that paint will help the core over the unfinished aluminum. Would it be possible you are confusing this with black anodizing? In that case the anodizing of a radiator actually improves the performance of it over unfinished but by painting it black it'd be like insulating the end tanks and anywhere else the paint touches. I could be wrong but I don't think any thickness of paint on heat exchangers is viewed as a good thing.

Don M

Do a quick search and see for yourself.

Look for "radiator, black paint, and heat rejection".

I cant believe this is actually being contested.

Don~

BoostdCTD

Well I read up more on this and everyone uniamously agreed that black is better than raw aluminum for heat transfer but as to the losses involved with anodizing and painting wasn't certain. Painting was generally considered worse than anodizing as far as hampering the heat transfer goes, but a major core manufacturer (Spearco) apparently markets an intercooler paint. I never knew anoziding hurt the heat transfer coefficient so much, I thought it was just a colored layer of aluminum....

HOHN

Check out the Eastwood catalog for their radiator paint.... Wonder why it's different than other paint, and goes on in really thin coats??

jlh