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Legacy Posts 07-04-2003 12:16 AM

Colors & Heat
Hi All
I was really wondering what the temp difference in two identical fiberglass RVs,sitting on the same spot in the exact same temp.One would be white and the other black.No A/C or fans.Windows open.

Legacy Posts 07-04-2003 12:23 AM

black absorbs heat - white reflects it.

And this is why my TT is white and SUV is black (?)....:o

:E :E

( I can't answer that question....specifically......)

Legacy Posts 07-04-2003 02:08 AM

try this
Put a black shoebox and a white one out in the sun with a thermometer in each.

For that matter, touch any black thing that has been in the sun.

Personally, I'd rather be in a white car in the summer.

Legacy Posts 07-04-2003 03:27 AM

Hi Thomas
Thats a good idea with shoe box thing.I know that white reflects and black absorbes.I guess Iwas just trying to find the exact difference.I will try that experiment.:wave

Legacy Posts 07-04-2003 09:07 AM

Black vs. White in the heat.
Your little experiment intrigued me, so I tried it yesterday using two identitical thermometers. I but the boxes on the front lawn and left them for an hour. The top was blown off the tube of the one in the black box. The thermometer in the white box was still intact. Thanks for the entertainment.

Legacy Posts 07-04-2003 11:27 AM

So are you saying you don't know what temperture the black one was. :lol I like that experiment too.

Legacy Posts 07-04-2003 01:13 PM

Hi All
I guess some of you had some fun with this.I never evan thought about doing comparism this way.Good stuff.

Legacy Posts 07-04-2003 02:08 PM

Black car?
If you really want a black car, they are deeply discounted in Phoenix! Wonder why? Must be the shoebox syndrome!;)

Legacy Posts 07-04-2003 02:17 PM

Wow. What an interesting experiment.

My two previous vehicles were white. They got terribly hot in the Texas summer heat. Neither had a sun roof.

Really wondered if I had gone insane buying a black car with a sun roof in the Texas heat. Well, truth be told, I cannot tell one bit of difference between the black car and the two white ones I had. Beats me. I know the theory and it makes perfect sense. Maybe it's just that metal is metal and it's gonna get hot regardless.

Only thing I don't like is that it's really hard to keep clean and shiney...especially when it's used as a tow vehicle for a camper :o

Still won't paint my trailer black to match. Really don't want to test it that far. :wink

Legacy Posts 07-04-2003 09:02 PM

Probably the reason the black car isn't much hotter than the white is because most cars are heavily insulated to reduce the amount of noise that bounces around the interior of the car (tin box). The insulation also retards the flow of heat into and out of the car, even though that was not primary purpose.

On the fiberglass RV's, few of them are insulated with more than a fraction of an inch of foam. So I would think changing the color of a fiberglass RV from white to a darker color would allow a lot more heat buildup than making the same color change to a car.

As for me, I prefer a white car and a white RV.

Legacy Posts 07-04-2003 10:56 PM

Black Vs. White
I always wondered about this when travelling through the southern states, and wondered if some of the State Troopers I met in black patrol cars weren't half baked. I sure agree with the hard to keep looking nice part, and white is right behind orange and yellow as highly visible colors for vehicle safety.

Legacy Posts 07-05-2003 08:32 AM

I believe most of the heat buildup in cars is through the glass windows as the light goes in and can't come back out since it is largely converted to infrared after striking an object (glass is mostly a barrier to infrared radiation). Hence, the green house effect. Auto headliners are insulated a bit and that might make black cars not too much hotter than white since most heat comes through the glass anyway. My Saturn Vue has "solar glass" which is claimed to reduce heat buildup. I have no idea if it works, lacking a Vue without "solar glass" to compare. If I lived in the South I surely would investigate further. Curiously black is not only a good absorber of heat radiation, its also a great emitter of heat. Thats why car radiators are black. But as the shoe-box experiment proves black is substantially better at absorbing than emitting.

Years ago I spoke with an Avion owner. When he coated the top of his shinny aluminum trailer with white rubber he claimed the temperature inside fell 10 degrees. Raw aluminum is most gray in color. I suppose I need to try the shoe-box experiment with white and aluminum foil tops to see if he was kidding.

Glad my Scamp is white.


Legacy Posts 07-06-2003 01:38 PM

That is correct
Regarding windows that contribute most of the heat build up in a car. The sun heats up the interior of a car through the windows but the windows do not let the infrared (heat) back out.

Our little eggs have much less glass than cars, and may also have curtains that can block much of the light from entering. In this case, the color of the exterior will play a greater role on our campers.

I vote white still

I'm very pleased that someone's tried the shoebox experiment. I really mentioned it as a mental example and not necessarily as a real test. It's really great that the theory was actually tested, although the results are still unknown.

How about this test....
put a couple of acetate windows in your shoebox sides......

Legacy Posts 07-06-2003 08:11 PM

FG should always be painted white..
I personally don't have any eoperience working with fiberglass. However, i have for many years been interested in building an airplane from a kit. There are many kit airplanes made with fiorberglass and they are all painted white. I guess that in the early days, the wings on some FG planes that were painted darker colors actually became loose and sagged. Requiring complete replacement. So, the rule of thumb is, when working with FG, paint it white...

Legacy Posts 07-07-2003 12:55 PM

In one of my previous lives, I was a paint dealer. The questions often came up about painting things like fiberglass or vinyl siding. The rule for vinyl is "Paint it any color your want, as long as it's no darker than the original color". I've actually seen vinyl siding melt and sag off the side of a house from being painted dark. The different colors of vinyl are formulated differently.

I don't think that the fiberglass or gel-coat is formulated differently for darker gel-coats, but the principle remains - you will be stressing the fiberglass more, by causing more expansion and contraction, with a darker color. Take a look at vintage Corvettes sometime. You'll see a lot more stress cracks in the darker ones.

In a car, most of the heat gain IS from the windows, but the darker colors do make a big difference, too. However, in Suz's case in Texas, it reaches a point where it doesn't make much difference - it's tough to tell the difference between 175 degrees and 195 degrees!

Legacy Posts 07-09-2003 10:06 PM

It ain't just black or white.........
I know, this should be in the jokes section, so spank the back of my hand...........

These two country boys were talking about the virtues of owning black horses vs. white horses.
First guy sez, ''We used to own white horses and black horses, but we got rid of the white horses because they ate too much hay.''
Second guy sez, ''Why do you think the white horses ate more hay than the black horses?''
First guy sez, ''We never could figure that out, unless it was because we had more white horses than we had black horses.'';)

Anybody know who told that story on an old shellac 78? (Scroll way down for the answer.)

Sorry, you didn't scroll far enough!:bed

Legacy Posts 07-10-2003 08:07 AM

Shellac 78
I'll guess...Spike Jones?

Legacy Posts 07-10-2003 10:07 AM

I'll guess as well: Bro. Dave Gardner?

Legacy Posts 07-10-2003 11:31 AM

amos and andy
jack benny
Pa kettle

Legacy Posts 07-10-2003 03:51 PM

Sorry, no gold ring yet.
Some good guesses, but earlier in the century than you're comin' up with. (But, Al, I'll bet Jack Benny might have used [read: stolen] that line, too. And it could have made a classic Amos n' Andy line.)

It was a team, two guys. Recorded on Columbia Records, 1920's. (I know, most of you were too young to remember!);)

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