IIRC the internal structures of the eye are much more sensitive to green compared to red. Its why even though both are limited to 5 mW, a green laser appears so much brighter than the red ones.

The human eye does respond to different colors differently. Visible Light and the Eye's Response That's for the normal human eye. Cats, dogs, and other animals have different response sensitivities.

As previously mentioned in this thread, there are a number of respected paracord sellers who offer luminous glow-in-the-dark and/or reflective paracord. You can get them in neon orange, neon green, etc. For visibility at night, there's nothing better.

In my view, if your going to be using paracord in the woods and want your paracord (or camp) to be spoted, consider using blaze or safety orange (not neon orange). It's just that you'll be shot at a lot less frequently due to mis-identification if there's hunter orange in close proximity to you. There's something to it - and also why a goodly portion of danger signs (like bridge out or unexploded ordinance) are orange.

I agree that the Type I (about 100#) [or Type II (400#)] paracord is something to be considered, and I thnk it's adequatly visible in plain white or neutral white - if that's the only color you can find it in. Unlike 550, I think a good portion of the Type 1 is real MIL-C-5040 or PIA-C-5040, so that's a bonus in addition to saving weight & space.

Now, I don't recommend this for just anyone (especially if your camping in Alabama or flying over Oklahoma), but purple and gold paracord tends to be a show stopper around here, day or night, and how! Go Tigers!!!!

I've seen blaze orange paracord, but don't remember where. Sorry.

i mark mine gear with the following:
- Bright neon yellow reflective tape.
- Bright red cordages with reflective threads in it.
- Glow in the dark and reflective cordage. (white)

Works great when wearing a headlight.

Golf balls are white for a reason.

Regards,
Bill

A few more thoughts on the subject.

First, most of our outdoor activities are in pretty heavily wooded areas, hilly to slightly mountainous terrain (think foothills of the Appalachian Mountains), no deserts around here. Orange cordage disappearing in fall leaves would be a DEFINITE possibility. I would have mentioned this before, but I honestly hadn't considered this. I assumed this would be a general issue, but like everything else, it seems dependent on environment.

DW bought me some bright orange nylon cord (unfortunately not paracord but it was still nice cordage) for christmas and it went into one of my kits. Now any time I open that kit that orange just jumps out at me, which is why I thought orange might make a good color choice. Others have made good points though that almost any color can disappear under the right circumstances (i.e. orange in fall foliage, tennis ball green in underbrush, white in the snow, etc).

I've noticed a lot of newer fire and emergency vehicles are a neon green (with a definite neon yellow undertone) rather than the ubiquitous red. I've also seen golf balls in the past in this neon green as well as orange.

Personally, I don't like the red, it never looks very bright to me, but it IS DS's favorite color so I thought it might give him a slight morale boost in a bad situation.

Also, not that long ago, I did a corded handle on a walking stick in something like a neon blue and that stands out VERY well.

I also hadn't given much thought to visibility at night so thanks for the suggestion on the luminous paracord.

Looks like I'll be ordering small quantities of each to compare before making a decision to buy 1000 feet of any one color. But then, you can never have too much cordage around the house, right?

FWIW - Here's a listing that shows which states and provinces require hunters to wear orange:

http://www.ihea.com/hunter-education/hunter-orange-requirements.php

I think the problem with all colors other than orange, including the reds, blues, neons, yellows, whites and even pink (Yuk!) is that they blend in (at least as to the human eye) with fungi, bark, colonies of lichens, mold, moss (that can have different shades of green & red in my area) and other things that grow on or around trees.

Even when the trees' leaves are turning color in the fall, the human eye tends to be able to distinguish the color orange from the leaves.

It's been my experience that colors appear differently in the forest than in direct sunlight. I think this is due to the impact (filtering) of the canopy and the color distortion caused by the ecosystem of the forest itself.

Everyday in a forest is like a heavily overcast day on the beach. Orange and lime green are the only two colors that don't turn gray to the human eye in low light conditions. If you've ever taken a black and white picture of a rainbow you may have noticed that it's the most prominent colors in the visibility spectrum that are no-shows in b&w.

In the timber management business (where timber landowners frequently paint exacting marks on trees surrounding the perimeter boundaries of tracts of woodland to discourage trespass and reduce adversarial possession) the best paint colors to use from a visibility standpoint are either orange or sometimes lime green. However, large timber companies generally use a uniform (companywide) color of paint scheme in their boundary line marking (e.g. yellow, dark blue, white), without much regard to visibility. It's kind of neat though to know who owns land simply by looking at the boundary line paint as you cross from one tract to the next.

Here's some typical remarks about colors found in forest management literature: "Red is not a preferred color. As it fades, it is difficult to see. Also, red is difficult to most people who are color blind." In any case, I still use a lot of red paracord because I like the color. Recently I found that red is one of the few colors that's available in 400 yard rolls (and sometimes in 700 yard rolls) of recently manufactured Certified C-5040.

I remember when I first started taking flying lessons. I was amazed by how much bright blues stuck out (think of those cheap plastic tarps). Earth tones all around with big blue dots everywhere (the dots were swimming pool liners). It just seemed to be an unnatural color.
The "best" color depends on where and "when" you are. Those bright oranges and yellows wouldn't be very good in the fall, when the leaves start to change & fall (I live in east PA).
We have a few guys in my motorcycle "gang" that line the rear of their bikes with alternating diagonal stripes of different colors & reflectivity. Then it's not just color but pattern too (diagonal stripes seem to scream 'man-made'). I'd think adding reflective strips would also help, especially in the dark. Does anyone make cordage in blaze orange and/or bright blue, with reflective white stripes thrown in?? They'd have to be changed every now and then when they get dirty.