I have been reluctant to make (or commission from Tim) insulated cuben gear like a quilt or a vest because I'm not fond of the bright white color. The colored cuben styles, like the breen, are an improvement but in the lighter products (like the 0.33 oz/yd CT03k.08) the color is very subtle, especially over white down.
I experimented with dyeing the cuben itself, but found that the necessary solvents and swelling agents weaken the film. I tried a dozen different formulas and found that a more chemically gentle dyebath didn't give much of a color.
So, I looked into dyeing the down. Down, like silk, is made of beta-keratin (a protein), and like silk it cannot be boiled (unlike hair and wool, which are alpha-keratin). Mercaptans and ammonia, common in hair dyes, are also likely to damage down. So I obtained five different kinds of dye for protein fibers and set about sacrificing some 800 fill down from thru-hiker.
I used Sebraset/Lanaset azo dye, washfast acid dye, fiber-reactive dye, ammonia-and-mercaptan-free hair dye, and Rit. All of these were dark brown. In each case I added about 2/3 oz (20 grams) of down to a warm dyebath and let it sit for exactly two hours. I then rinsed the down until the water ran clear and dried it in a pillowcase in a tumble dryer on low heat. I also tried leaving the down in a bath of Rit dye overnight. The results are below.
Pictured above are (clockwise starting at the top)fiber reactive, washfast acid, overnight Rit, two-hour Rit, hair dye, and Sebraset. The white sample in the middle is the undyed down. Most of them turned out some shade of pink. The trusty standby, Rit, gave by far the best color. I then decided to try creating a breen color with the Rit (below).
I then wanted to see how the dark brown and breen Rit samples looked under a layer of cuben. In the photo below is the brown under 0.33 oz CT03k.08 (left) and breen under 0.68 oz CT1k.08 (right).
The colors turned out well, I think, and it seems to me that almost any hue, including bright reds or blues, is possible. Colored down isn't worth anything if it compromises loft or durability, though.
The procedure for testing down fill power is complex (a 68.4 gram weight moving downward at a precise rate, etc.) and requires a vessel of particular dimensions. But I assume that the nominal fill power of the thru hiker down is accurate, so I just needed to compare it to the colored down. The set-up is shown below.
I added three grams of dry, fluffed down to a polycarbonate tube 10 cm in diameter and 30 cm in height. I then allowed a 14 gram disk to come to rest on top of the down, and recorded the volume of down in the tube. I performed thirty trials each of the Rit brown, the Rit breen, and the undyed white down. The mean volumes were:
white: 1570.7 cubic cm
brown: 1596.3 cubic cm
breen: 1601.4 cubic cm
The greater loft of the dyed down could be attributable to greater cleanliness due to the post-dyebath rinsing cycles, but it is probably not significant. A t-test for a difference in means showed no statistically significant difference at the 95% confidence level (in case anyone is interested).
I was also concerned that embrittlement or other minor damage from the dye process might not be revealed by the loft test (but might affect the down after many compression cycles). So I examined the down under the microscope. Below are the white, brown, and breen down at 100x:
There is no visible crimping or breakage of barbules. The dyed and undyed down are indistinguishable under the microscope.
I think the colored down under standard cuben gives a cosmetically better result than white down under colored cuben. Deeper and darker colors are possible, more color options are available, and the dyeing process is gentle. Any ideas and feedback are welcome.