Black paint - hotter car?

How much hotter would a car painted back be compared to the same car
painted silver if you leave them outside on a sunny day?

"Johnny" > wrote in message
om...
> How much hotter would a car painted back be compared to the same car
> painted silver if you leave them outside on a sunny day?

I would think that the size of the greenhouse area is what dictates any
difference "inside the car". The sheetmetal on a black car might be hotter to
the touch, but I doubt that this makes a big difference on the inside.


--
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Rick Brandt wrote in alt.autos

> "Johnny" > wrote in message
> om...
>> How much hotter would a car painted back be compared to the same car
>> painted silver if you leave them outside on a sunny day?
>
> I would think that the size of the greenhouse area is what dictates any
> difference "inside the car". The sheetmetal on a black car might be
> hotter to the touch, but I doubt that this makes a big difference on the
> inside.

Having owned many cars of many different colors, I will state
that black cars are always hotter by several degrees than
lighter cars.
>
>



--
Dick #1349
"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety."
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Home Page: dickcr.iwarp.com
email:

On 28 Aug 2004 13:23:09 -0700, (Johnny)

>How much hotter would a car painted back be compared to the same car
>painted silver if you leave them outside on a sunny day?

A few months ago, I did a rather unscientific test. And I didn't record
the results anywhere except my head, so this is as best as I remember.

A co-worker and I put a thermometer in his car and left it for a while
(at least 30 minutes). It was a light-colored (grey or silver) Honda,
he was not using a windshield shade and the non-tinted windows were all
the way up.

The thermometer read somwhere between 125 and 130 when we took it out,
walked over to my car, a black Sebring convertible with black cloth top
with untinted windows rolled down an inch or 2. I did have a windshield
shade.

The thermometer had dropped to between 105 and 110 by the time I put it
in my car. I was impatient to see the results, so I only left it in
there a few minutes, but I did check and after a relatively quick rise
to between 110 and 115 it didn't seem to be rising any more.

Both cars were in full direct sunlight parked on black asphalt.

So, mine was cooler despite being black although I don't know which of
the 3 factors that could have been acting in my favor is most
responsible.

This is my guess:

1: Cracking the windows. I can't prove it (without doing more tests),
but I believe this is the biggest factor.

Tie:

2/3: Cloth top. I suspect that probably breathes better than a
hardtop, even though it is watertight.

2/3: Windshield shade. I've heard varying opinions on whether these
are any good for temperature. Some claim they only prevent your
dashboard from cracking. I don't believe it can make it any hotter.

--
There's no way to delay that trouble comin' everyday

Johnny wrote:
> How much hotter would a car painted [black] be compared to the same car
> painted silver if you leave them outside on a sunny day?

There is no way to answer this question without knowing all kinds of
details about how each car is built (what materials, over how much area,
and so forth) and how hot it was outside. But in general, the black car
should absorb more heat and should stay hot longer.

John David Galt > wrote in
:

> Johnny wrote:
>> How much hotter would a car painted [black] be compared to the same car
>> painted silver if you leave them outside on a sunny day?
>
> There is no way to answer this question without knowing all kinds of
> details about how each car is built (what materials, over how much area,
> and so forth) and how hot it was outside. But in general, the black car
> should absorb more heat and should stay hot longer.
>
>

But black also radiates (loses) heat better,that's why electronic heat
sinks for integrated circuits are black.

--
Jim Yanik
jyanik-at-kua.net

Having used one of those portable black-tank camper showers, I do know they
get substantially hotter than a silver-tank unit.

We also, for fun, did a reading with an electronic infrared thermometer of
car finishes a few weeks ago. The lowest in the sun was white. Next was
silver, then metallic blue, and finally black being the hottest. The
surface temperatures ranged from 130 to 182 degrees (black car). My
brothers blue metallic car is far to hot to grab the steering wheel whereas
the white car wasn't too bad.

Also, watch the delivery drivers of UPS and FedEx. The darker UPS truck's
driver always seems more uncomfortable and sweating more than the FedEx
drivers in the white trucks.

B~

John David Galt wrote:
>
> Johnny wrote:
> > How much hotter would a car painted [black] be compared to the same car
> > painted silver if you leave them outside on a sunny day?
>
> There is no way to answer this question without knowing all kinds of
> details about how each car is built (what materials, over how much area,
> and so forth) and how hot it was outside. But in general, the black car
> should absorb more heat and should stay hot longer.

Moreover, the difference between a silver and a white car is
significant.

--
Cheers,
Bev
=/=\=/=\=/=\=/=\=/=\=/=\=/=\=/=\=/=\=/=\=/=\=/=\=/=\=/=\=/=\=
"Sure, everyone's in favor of saving Hitler's brain, but when
you put it into the body of a great white shark, suddenly
you're a madman." --Futurama

I own a silver 2005 Lincoln LS and a black 2003 Mustang
GT convertible. When I get into either one after they sit in the
hot sun the temperature inside is the same.


mike hunt



"Mike Z. Helm" wrote:
>
> On 28 Aug 2004 13:23:09 -0700, (Johnny)
>
> >How much hotter would a car painted back be compared to the same car
> >painted silver if you leave them outside on a sunny day?
>
> A few months ago, I did a rather unscientific test. And I didn't record
> the results anywhere except my head, so this is as best as I remember.
>
> A co-worker and I put a thermometer in his car and left it for a while
> (at least 30 minutes). It was a light-colored (grey or silver) Honda,
> he was not using a windshield shade and the non-tinted windows were all
> the way up.
>
> The thermometer read somwhere between 125 and 130 when we took it out,
> walked over to my car, a black Sebring convertible with black cloth top
> with untinted windows rolled down an inch or 2. I did have a windshield
> shade.
>
> The thermometer had dropped to between 105 and 110 by the time I put it
> in my car. I was impatient to see the results, so I only left it in
> there a few minutes, but I did check and after a relatively quick rise
> to between 110 and 115 it didn't seem to be rising any more.
>
> Both cars were in full direct sunlight parked on black asphalt.
>
> So, mine was cooler despite being black although I don't know which of
> the 3 factors that could have been acting in my favor is most
> responsible.
>
> This is my guess:
>
> 1: Cracking the windows. I can't prove it (without doing more tests),
> but I believe this is the biggest factor.
>
> Tie:
>
> 2/3: Cloth top. I suspect that probably breathes better than a
> hardtop, even though it is watertight.
>
> 2/3: Windshield shade. I've heard varying opinions on whether these
> are any good for temperature. Some claim they only prevent your
> dashboard from cracking. I don't believe it can make it any hotter.
>
> --
> There's no way to delay that trouble comin' everyday

"B. Peg" wrote:
>
> Having used one of those portable black-tank camper showers, I do know they
> get substantially hotter than a silver-tank unit.
>
> We also, for fun, did a reading with an electronic infrared thermometer of
> car finishes a few weeks ago. The lowest in the sun was white. Next was
> silver, then metallic blue, and finally black being the hottest. The
> surface temperatures ranged from 130 to 182 degrees (black car). My
> brothers blue metallic car is far to hot to grab the steering wheel whereas
> the white car wasn't too bad.
>
> Also, watch the delivery drivers of UPS and FedEx. The darker UPS truck's
> driver always seems more uncomfortable and sweating more than the FedEx
> drivers in the white trucks.

Appearances can be deceiving. Many years ago as a college
project we had to build solar collectors. As part of the
process we researched coating and colors. In most cases
things that appear to be "black" do absorb more energy.
However, there are cases where other coatings that appear to
be a lighter color actually are better infrared absorbers
and therefore can aborb more energy. Or another way of
saying this - Things that appear to be black in the visible
spectrum may or may not be black at other frequencies and
this can have an effect on the overall amount of energy
absorbed. However, in most cases, if it looks black in the
visible spectrum, it is probably also "black" at other
frequencies as well.

Ed