painted rads
 

I see a lot of people have painted rads. Obviously this will make them perform not as well as a naked rad. My friend brought up a very good question: why not powder-coat it? Its not horribly expensive, and would probabily preserve the cooling abilites well enough. Along that line, how much is the cooling reduced with a painted vs naked core? Ive seen from 1C up to 5C but I want some experiance talking here. Im thinking of bringing my rad from the inside of my case to the top, and its a naked one. since i have a silver case Id probabily build a box since silver paint looks dumb (mmm chromed rad anyone?), but my friend has a black case and we were discussing how hes going to do his future WC system (i sold him my old system for the price of my new pump).

Any thoughts as to why automotive radiators are pretty much all painted black? IMHO it's for corrosion protection but doesn't harm performance.
There is paint specifically for radiators.
I have tried before/after with radiator paint (but not PCs - race bike oil radiators). Results in that situation - zero difference in temps (same lap times so at least approx same heat input and airflow).
The powder coatings I've seen have been significantly thicker than paint (even thicker than catalitic paints like Imron). I'd expect it to be more insulative than paint and thus terrible as a radiator coating. I've never tried it, though...

Normally, when you paint a radiator the paint doesnt penetrate deep into the core. The inside of the core is what cools the water. If you look inside a standard heatercore you wil notice that there are actually thousands of pins that go between the tubes rather than a zig-zag sheet of copper. This increases surface area and turbulence in the rad. So basically, painting the outside will have very little to do with temps.

Powder coating, however, completely covers the entire area, correct? This would be bad.

well, i'm looking at, for instance, a black ice:

http://www.dangerden.com/mall/Radiators/hwlabs.asp

so what youre saying is, its just the edge of the fins that are painted? i'm wondering how I can accomplish that for my friend. for myself I have a big shroud I'm going to try to mount to the top of my case (assuming I can power two 48v fans that put out 50db each...with 200 CFM each :D)

Yes, the paint doesnt really go deep into the core. If it did, it would be bad.

ok then. so I guess the only way to get it like that is to make a thin layer on something, then set the core on it? the top probabily doesnt even matter because the fans will probabily be in the way, and the sides i never thought would be bad to paint. i just cut off some extra things that stuck off my possible future shroud. i have determined from testing that my temps do not change no matter if my fans are at 7v or 12v. I hope this can bring a change.

Just spray paint it at an angle. The paint will cover the fins a few mm inward at most, leaving the inside areas bare.

an acid bath and nickel coating would be hot.....i wonder how much that would cost....

Not alot. You can buy kits to do that pretty easly at home.