Paint &electronics.

[MP1]

....and the moral of this story is.....
Do not use plastic as a heat sink?..

;D ;D ;D

but seriously, you have a real problem accepting this, so I will quit. In my last post I was just trying to point out that the difference is not color, it is the difference in the metals.
Here is a link that also explains: http://www.anandtech.com/showdoc.aspx?i=1115&p=2
Some good reading regarding heat sinks in this link.
It is a common myth about the color.

We stopped anodizing the aluminum black in our manufacturing house about 10 years ago. Since then we have used clear anodizing. Works really nice and does not look like crap years down the road.

Congratulations on your home-made aluminum foil thermos.

MP

 

[Alun]

....and the moral of this story is.....
Do not use plastic as a heat sink?..

;D ;D ;D

but seriously, you have a real problem accepting this, so I will quit. In my last post I was just trying to point out that the difference is not color, it is the difference in the metals.

Here is a link that also explains: http://www.anandtech.com/showdoc.aspx?i=1115&p=2
Some good reading regarding heat sinks in this link.
It is a common myth about the color.

Oh I do accept this, the colour isn't the main thing that determines the efficiency of a heatsink I wasn't meaning to imply that it is. In some circumstances the colour doesn't make much difference where forced air cooling is used. I've done a bit more research now and it seems the reason the colour makes a bigger difference with the heatsink I was using is because of it's construction. It's a large piece of flat aluminium with fins on the back, the large flat surface is the part that dissipated the energy more by radiation than convection.

According to the article the difference in metals doesn't matter to much either, aluminium is use despite being a poorer thermal conductor than coper which is just used as a conductive pad on some heatsinks. I believe the shape is more important and whether convection or forced air cooling is used, I'd imagine that the use of heat conductive paste and insulating washers and rubber makes a big difference too. Perhaps the radiator argument applies here too, radiators don't emit most of their energy by radiation they do by convection or forced air cooling, this also depends on the construction too.

We stopped anodizing the aluminum black in our manufacturing house about 10 years ago. Since then we have used clear anodizing. Works really nice and does not look like crap years down the road.

Are you sure it wasn't just to save money?

Congratulations on your home-made aluminum foil thermos.

I did this experiment in way back GCSE sience class.

 

[ante1]

I have to say; if you don

 

[MP1]

Are you sure it wasn't just to save money?

No, like I said, we still anodize. Just not black. The White powder that ante has mentioned is exactly what I was talking about in an earlier post. The metal must have a finish to withstand the elements of the atmosphere. Otherwise, you are just wasting your money. Not to mention, you would not keep long term customers by selling something that is bound to fail later on.

MP

 

[oldgrandpainmi]

Hey Guy's,

Can I add my 2 cents?

Andodizing and painting are just one aspect.  Here is a thought:

If color is not a major concern, why not get some gun bluing or browning for steel parts, and/or, gun aluminum bluing for aluminum?  I had to check this out, but I threw my meter across the barrel of the rifle I just did and it conducted!  Depending on the amount of bluing you want, you can get a dark blue to almost black, just by repeating applications.  Won't come off due to heat.  My 8mm Mauser gets hotter after 12 fast shots than any of my heatsinks.


The cost for bluing is $4.00 a bottle.

oldgrandpainmi

 

[65ShelbyClone]

Now as long as you don't leave them in the sun or in front of a fire the unwrapped bottle will cool down more quickly than the wrapped one.

Are we assuming that the foil is making an unrealisitic 100% full contact with the entire plastic bottle, or just as good as one can practically do in the five minutes to conduct the experiment? Since I tend not to use "theoreticallies" for support, I'll address the practical aspect. Not accounted for is the layer of air between the foil and the bottle. This will noticably slow the heat rejection of the bottle.

Something else to ponder is the fact that most aluminum car radiator cores are not painted at all. Brass and copper radiators are soldered and brazed together in manufacturing and look horrible until they are painted with black paint specifically for heat exchangers.

To answer the original question of this thread, you can use high-temp engine enamel from the autoparts store. It can withstand more heat than whatever the heatsink is cooling.

 

[MP1]

Andodizing and painting are just one aspect. Here is a thought:

If color is not a major concern, why not get some gun bluing or browning for steel parts, and/or, gun aluminum bluing for aluminum?

Wouldn't you have to keep up the bluing from time to time? Not trying to give you a hard time. I just do not know anything about gun bluing. I thought that this was not a one time process; that you have to continue to blue it from time to time.

MP