The heat is in the IR region that you do not see with your eye. In the
IR spectrum things look very different. If you've ever looked at
things using an IR sensitive camera you'll see what I mean. I think
bees see in IR, and I noticed that flowers reflect a lot of IR even
though they may seem like very dark rich colors to the human eye.
Typically darker colors do absorb more IR however, but its more of a
coincidence than a requirement. Those handheld non-contact temperature
sensors are really cheap these days. You could make a sample sheet
with swatches of color, put it in the sun for 30 minutes, then shade
and measure immediately. See what kind of differences you get.

If anyone is wondering why I was looking at flowers with IR sensitive
cameras, it was part of testing a series of IR cut filters for a camera
we were designing. A group of flowers is a stereo typical test subject
for a color camera.

You could make an IR pass filter (daylight filter) from a piece of
exposed film negative. Put it in front of a black and white TV camera.
Then point it at your test subjects. The ones that are the brightest
are relecting the most IR and should be the coolest.

BTW, the touch test may not be a very good test because your finger is
really measuring the amount of heat rather than the absolute
temperature. Put another way, touching a 150 degree F piece of
plywood, or a 150 degre F piece of aluminum, you'll think the Al is way
hotter because the Al will transfer more heat to your finger.

firstflight wrote:
I have a composite kit aircraft, and it is time to paint! But I just hate
the idea of painting it WHITE (like most all the others). I understand that
HEAT is a big factor in this decision, and that white attracts the least
amount of heat which could disrupt the Epoxy over time. Since my plane is
held together with Epoxy, this seems like a valid concern.

What do you think people? Does it have to be white?? Could one choose a
light yellow, light gray, silver,etc....... and not be pushing the envelop
too much?

I happen to live in a very cool part of North America, so I am not too
worried about regular heat (like someone in Arizona might be).

Thoughts?