Dare you to make sense of colors

[wisenber]

i use silver on the inside just because its pretty much just a generic color. more eyebrows would be raised in question if the underside of my quilts were yellow, or red.. silver is just like gray is for tarps.. there.

Say it isn't so! Here I thought you'd funded a five year NASA study on the matter before I got my Te-Wa!

FWIW, I do like the silver and black color of my UQ, but for some reason I keep waking up in the middle of the night wondering why the Raiders aren't doing better.

[gargoyle]

Colors of fabric-
In the quiltworld, colors are important in distinguishing the inside from the outside, especially in differentially cut underquilts. I like it for easy identification on my topquilts, also.

I have a hard time believing the dark fabric vs. light fabric has a lot of actual thermal difference. Be it heated by the sun or your body. We are talking about super thin, generally breathable fabric. Any puff of wind will move any retained heat.

If black was a truly superior color in heat retention/absorbtion, all Arctic-rated expedition gear (tents, sleeping bags, jackets, pads, etc.) would be black. More often it is some bright color. Take a look at any summiting member from Everest or the like.
Some of the color choice has to do with customer appeal. Some has to do with safety. Some has to do with blending into your environment (camo or white).
I'm sure the big gearmaking companies have tested the thermal qualities of one color vs. another.

[wisenber]

Colors of fabric-


If black was a truly superior color in heat retention/absorbtion, all Arctic-rated expedition gear (tents, sleeping bags, jackets, pads, etc.) would be black.

Try comparing the temperature of a black or dark colored leather seat to a lighter colored leather seat in a car in the middle of summer wearing shorts- same material, different color, different temperature.

[Owl]

Colors of fabric-
In the quiltworld, colors are important in distinguishing the inside from the outside, especially in differentially cut underquilts. I like it for easy identification on my topquilts, also.

I have a hard time believing the dark fabric vs. light fabric has a lot of actual thermal difference. Be it heated by the sun or your body. We are talking about super thin, generally breathable fabric. Any puff of wind will move any retained heat.

If black was a truly superior color in heat retention/absorbtion, all Arctic-rated expedition gear (tents, sleeping bags, jackets, pads, etc.) would be black. More often it is some bright color. Take a look at any summiting member from Everest or the like.
Some of the color choice has to do with customer appeal. Some has to do with safety. Some has to do with blending into your environment (camo or white).
I'm sure the big gearmaking companies have tested the thermal qualities of one color vs. another.

I'd suspect that the reason that most artic rated expedition gear is bright colored has to do more with the ability to spot the gear in those conditions than it has to do with thermal properties. Red/orange is far easier to spot on a snowfield than white/silver...or even black.

I would have to say it's been pretty much proven that black does absorb longer wavelength radiation...for a test, take a white trash bag and a black trash bag outside during the winter on a cold, clear sunny day, spread them out, and throw a little snow or ice on them...see which melts faster.

I don't know about black radiating away heat as easily at night...I think it just gets hotter during the day, so it retains more heat to actually radiate away, whereas lighter colors absorb far less, and so have less to lose when it cools.

[Harstad]

I dont know much about the topic. But I remember from biology class the teacher claimed that furred animals change to white in wintertime, not only as a mean of camoflage but also because it reduced heat loss - giving less need to replace energy when food is sparse.

Took a google sweep and found this (quote on bottom). It claim that aluminum color only radiates 1/3 of the energy of any other color. In my head that transform that the heat loss (by radiation) is 66 % more when the fabric has a colored surface.
Now because of the temperature gradient in a TQ I dont think the actual heat loss is af any significanse.



But there is also the heat loss by covection and conduction to take into account...

BTW the polar expedition clothing colors serves the purpose as signal/marker and they look better on fotos/film. Take a look at nature photographers, when they include a tent in their foto is is likely to be brightly colored to give contrast/vividnes.

my .5 kroner



"FACILITIES INSTRUCTIONS, STANDARDS, AND TECHNIQUES
Volume 3-7
PAINTING OF TRANSFORMERS AND CIRCUIT BREAKERS
...
SECTION 3 - HEAT LOSS BY RADIATIONHeat loss by radiation depends on the formula

Wr = KE (T24 - T14)

Where

Wr = watts loss per square meter by
radiation
K = 2.37 x 10-14 T2 = hot body tem*
perature in absolute degrees
T1 = ambient temperature in absolute
degrees
E = emissivity factor

The value of E for aluminum paint is 0.55;for
mat black paint 0.95; and for practically any
other paint 0.90 to 0.95. An aluminum painted
transformer will therefore dissipate by radiation
approximately 1/3 less heat than a transformer
painted some other color."

[Just Jeff]

I don't know about black radiating away heat as easily at night...I think it just gets hotter during the day, so it retains more heat to actually radiate away, whereas lighter colors absorb far less, and so have less to lose when it cools.

Research emissivity.

[DavyRay]

Research emissivity.

Psychology trumps science most of the time. Bright orange is a warmer color than black. Ta Da!

I do think that very smooth, shiny, light surfaces do not warm from radiation as quickly as dark rough surfaces. I also think that the difference would be not measurable outside of a lab with calibrated instruments. And that is only radiated energy. Convection would probably overwhelm any effect on radiated IR between layers.

[Just Jeff]

Psychology trumps science most of the time. Bright orange is a warmer color than black. Ta Da!

Ha...probably right!

I do think that very smooth, shiny, light surfaces do not warm from radiation as quickly as dark rough surfaces. I also think that the difference would be not measurable outside of a lab with calibrated instruments. And that is only radiated energy. Convection would probably overwhelm any effect on radiated IR between layers.

I think this is all correct, as well.

[DemostiX]

I'm taken with the experience of climbing on a black motorcycle saddle in the sun in the summer.

But a quilt is different. The insulation is of the thermal variety for the quilt. That strikes me a problem in two ways. First, the heat source, the sun, is always above the quilt. While there's no problem drying off a moistened black DWR textile surface that way, the layer of air just below the surface, warmed by radiation, will tend to remain there, rising up against the surface, rather than diffusing and mixing with high-humidity air from a partly wet quilt. We'd like to turn the insulation off, but if the quilt is just slightly wet, the insulation will ..........insulate. So, it would seem that the black interior of quilts sewn into bags might dry more quickly in a clothes dryer than ones with a silver interior finish, but not that much faster in the sun.

That said, there's probably been a camping equipment mag that addressed this with an experiment 30-40 years ago. Say: spray two bags with equal amounts of water, carefully weighted. Seal each in a plastic bag for a couple of hours for diffusion through the insulation. Then place them both in the sun for a time, one with black surface up, the other with light surface up. Weigh them before and after each of several intervals to see whether black-to-sun dries out, loses its water-weight appreciably faster.