Black (dark) fabric and the sun

[Raistlin 0]

Hi,
As we all know, UV destroys the fabric the canopies are made of, that's why we don't leave them hanging out in the sun. Now, a snow-white canopy will probably deflect more UV rays than a midnight black one, right? Is it then safe to assume that in the long run bright-colored canopies are more durable than dark-colored ones (perhaps for only a few tens jumps, but still), as they adsorb less UV?

[slotperfect 7]

i'm sure the lighter colors will attract less heat, but I'm not sure about UV. I'm sure the scientific types will jump into the thread shortly with a good answer. They were tearing it up over in the Polarized Sunglasses thread.

Arrive Safely

John

[cobaltdan 0]

its the other way around:

darker colors block more uv than lighter colors.

sincerely,

daniel preston
atair <><>

Daniel Preston <><>
atairaerodynamics.com (sport)
atairaerospace.com (military)

[mnischalke 0]

At the pd factory, I seem to recall being told that the fluorescent colors degrade faster in sunlight than any other color.

mike

Girls only want boyfriends who have great skills--You know, like nunchuk skills, bow-hunting skills, computer-hacking skills.

[diablopilot 2]

Quote

At the pd factory, I seem to recall being told that the fluorescent colors degrade faster in sunlight than any other color.

I don't think the material degrades any faster, but the dyes break down quicker.

----------------------------------------------
You're not as good as you think you are. Seriously.

[RevJim 0]

Quote

its the other way around:

darker colors block more uv than lighter colors.

sincerely,

daniel preston
atair <><>

Block yes, Dan, but I believe also a bigger issue is absorbtion vs. reflection.

Black absorbs light, white reflects light. Black is good for blocking light and creating/trapping heat, while white is good for reflecting light as well as heat.

As far as degredation, I don't know. I've heard both sides of the story, but was specifically warned against buying used black gear from the desert states.

Actual technical specifications would be good. Kallend perhaps?

It's your life, live it!
Karma
RB#684 "Corcho", ASK#60, Muff#3520, NCB#398, NHDZ#4, C-33989, DG#1

[mnischalke 0]

Like I said, I don't recall the conversation exactly, but I think the word degrade was used. I do remeber being quite surprised.

mike

Girls only want boyfriends who have great skills--You know, like nunchuk skills, bow-hunting skills, computer-hacking skills.

[cssriggers 0]

Quote

At the pd factory, I seem to recall being told that the fluorescent colors degrade faster in sunlight than any other color.

There was a great presentation at the last PIA symposium about these issues (heat, light, water, etc affecting canopy fabric.) It was given by Jeff Quill, as I recall.

Basically he said the UV damage is based on free radical activity. And since fluorescent-colored fabrics already contain free radicals, the degradation process is accelerated in the presence of UV exposure.

We've seen in the field that fluorescent fabrics seem to degrade more quickly. It was cool to hear a technical reason for it.

Alpha Mike Foxtrot,
JHL

[nicknitro71 0]

Quote

Block yes, Dan, but I believe also a bigger issue is absorbtion vs. reflection.

Black absorbs light, white reflects light. Black is good for blocking light and creating/trapping heat, while white is good for reflecting light as well as heat.

As far as degredation, I don't know. I've heard both sides of the story, but was specifically warned against buying used black gear from the desert states.

Actual technical specifications would be good. Kallend perhaps?

Black does not reflect any of the visible light. white on the other hand refects all the visible light color spectrum.

UV light is reflected and absorbed virtually equally by all colors. Talking about UV light and colors does not make any sense because visible light and UV have very different frequencies and wavelenghts.

For instance, the reason why you need a back light bulb to see floreshent colors is because the bulb will not refect the visible light but only the UV. A white bulb just refects everything. UV light is essential for seeing florescent glows.

Anyhow, UV light effects all canopies equally (but florescent ones that are effected to a larger extent). A black canopy will get more damaged by the heat produced by the visible light than a white one.

Memento Audere Semper

903

[cobaltdan 0]

fluorescent dye colors fade quicker, however this has nothing to do with damage to the fiber and structural integrity.

i.e. whites contain a brightener, a fluorescent dye usually made from a class of chemicals called courmarins. they absorb a small percentage of the light falling on them and re-radiate light in another spectrum. this action tapers off over time and is independent of any light degradation of the fibers.

dark color dyes protect the fibers from uv damage better than light colors, however in the context of skydiving canopies. get what ever color ytou fancy, and have fun. effects of the color are minimal.

sincerely,

dan<><>
atair

Daniel Preston <><>
atairaerodynamics.com (sport)
atairaerospace.com (military)

[mraviation1 0]

I don't know anything about the scientific end of all this, but I have a friend how conducted a real world test. He took several samples of canopy fabric of the same type, the only difference was the color. He made sure of the age, type and kind of fabric. The samples were placed in the desert sun in an unshaded place for 2 weeks then retrieved for a pull test to test the integrity of the samples. to my suprise the black fabric held up the best. I am not sure why. The person who did the test is very educated in gear and a master rigger. Just my 2 cents