"Wayne Paul" wrote in message
...

"Peter Dohm" wrote in message
. ..

"Bob Kuykendall" wrote in message
oups.com...
Earlier, Jim Weir wrote:

...Isn't a perfectly reflecting surface much better than
one that doesn't reflect the energy?...

In theory, yes.

In practice bare aluminum, even highly polished bare aluminum, absorbs
enough energy in direct sunlight to threaten some materials used in
bonded aluminum.

Thanks, Bob K.

Despite the obvious glare of visible light, polished aluminum absorbs far
mor solar energy than white.


This was discussed a while back. For details see
http://www.soaridaho.com/Schreder/Co...olor_Temp.html

Wayne
HP-14 "6F"
http://www.soaridaho.com/Schreder

The following is from Bellcore. The first number is the solar energy
absorbed the second is the low temperature heat radiation. As you can see,
polished alumunum absorbs only slightly more than white paint but radiates
only 6% as much heat. In other words, although it absorbs little, it
radiates much less so it heats up more than any painted surface.

Polished Aluminum .15 .06

White .14 .97

Yellow .30 .95

Cream .25 .95

Light Grey, Green Blue .50 .87

Med. Grey, Green Blue .75 .95

Dark Grey, Green Blue .95 .95

Black .97 .96



Bill Daniels