There are those who say the itch caused by wool is due to the detergents used to process it. There are others who say that wool is inherently itchy. There are few, however, who would recommend wool as a fiber for making fabric for under garments. The United States Department of Defense (DOD) is among the few that believes wool underwear might be just the thing for American soldiers. The DOD wants soldiers to try out woolen underwear made from fabric that has been treated with a new process called biopolishing.
No Itch: “Feels Just Like Silk”
“The fabric we just finished October 25th feels like silk,” says Jeanette Cardamone, a researcher at the U.S. Dept. of Agriculture’s Ag Research Service (ARS) Eastern Regional Research Center in Wyndmoor, Pennsylvania. “We’re not telling the guys who are field testing these undershirts in battle what it is. It’s hard to get past the itch factor. But this is machine washable wool and it feels like silk.”
The woolen fabric is silky and machine-washable because of the hydrogen peroxide and enzymes used in the two step biopolishing process that Cardamone and her ARS colleagues have developed.
Dr. Cardamone and a colleague in the laboratory.
The biopolishing whitens and then eliminates, or smoothes the scales on the wool fibers. The scales are what allow wool fibers to felt. They, along with the “crimp” of the fiber, give wool yarns much of their “wooly” body. In many applications wool would not be wool without its tiny scales which, when magnified, look like the shingles on a roof.
When you say “felt” there are generally positive connotations with the word. When you say “shrink” there are generally negative connotations. But felting, which is possible because of the scales, is only controlled shrinking. The scales are one of wool’s features that make it both uniquely valuable and, at the same time, limit its application. Biopolishing creates new applications for wool by removing the scales on woolen fibers without destroying their other positive features.
“We use an enzyme to polish the surface of the wool fiber and smooth the scales,” Cardamone said. “This is important because when agitation and ressure-along with temperature-causes the scales to lock together you lose dimension on the fiber. This is what’s called shrinking.”
Two Simple Treatments
The novel ARS process involves treating the wool in 30 degrees Centigrade (86 F) bath of activated hydrogen peroxide for 30 minutes. That bleaching process is followed by a bath in the enzyme mixture for 40 minutes at 40 degrees Centigrade (113 F). The bleaching time is shorter and the temperatures are lower than what are currently the norm.
“High-temperature dyeing is traditionally used with wool because of the lipid (wool grease) barrier to dye uptake,” Cardamone said. “Although wool has resilient properties, those high temperatures weaken the fiber. Our process lets wool be dyed at lower temperatures, preserving its strength.”
Wool before treatment (left) shows scaly surface. After Treatment (right) scale is gone.
The same lipid layer that makes wool resistant to dye uptake would protect the scales against such an enzyme attack. But bleaching removes the lipid protection.
“No damage is done to the underlying fiber structure, and the fabric’s mechanical properties are not changed, because the enzyme activity is limited to the outside layer, or cuticle,” Cardamone said.
An additive is used in both the bleach pretreatment and the enzyme treatment to keep the enzymes out of the fiber’s inner structure.
Textile mills will not have to retool to use biopolishing, however.
“We designed the process so that textile mills can use their existing equipment and their existing protocols,” Cardamone said.
Using biopolishing to make woolen textiles machine washable will be a boon for the American wool market. Machine washable woolens available in the U.S. today are imported. That is because chlorination, the process used to make them machine washable, is banned in the U.S. for environmental reasons.
Today’s Military Is Wearing Wool Skivvies-In Comfort!
The first purchase of biopolished machine washable woolen undershirts required 12,000 yards of 60 inch wide knit jersey. That order was for the U.S. Army. There is discussion about the Air Force adding to the order. The fabric was 100 percent American wool, thanks to the Berry Amendment of 2004. That amendment requires uniforms to be made either from all American products from the raw fiber forward, or from a country with which the U.S. has a free trade agreement.
“This will be great for the wool market because we have a customer right now and we’re expecting that the process will find its way into the commercial market,” Cardamone said.
How Your Flock Can Get In On The Profits
Commercialization, other than for the military market, is still in the trial phase. The ARS process for machine-washable, itch-free wool biopolishing is patented and must be licensed by the firm or individual that uses it. No licensing is required for the mills that fulfilled the military contract. No commercial licenses have been issued yet.
“This is patented and still in the trial phase,” Cardamone said. “That means if somebody is interested they can sign a confidentiality agreement. They can’t divulge the recipe or the procedure for the process but they can try it and see if it’s practical for them. If they find out it is they can license it. At this point they can use the process for experimentation but not for commercial purposes.
“I’m a hand spinner and weaver and go to some of the wool festivals,” Cardamone continued. “When I talk to people who market their own wool they say they want to see this process done at the fiber stage. They want to knit with it or weave with it. This can open up another market for them. We do have people trying it out in the yarn stage.”
Trials are currently under way to determine biopolishing’s success with yarns and loose fibers, according to the American Sheep Industry Association, which provided partial funding for the biopolishing research through the American Wool Council.
“If a person wants to be in the textile market this would be ideal,” Cardamone said. “If you are at the fiber stage you’d have to market it as shrink proof fiber.”
Anyone interested in experimenting with the biopolishing process can contact Cardamone by email at firstname.lastname@example.org or by phone: (215) 233-6680. For a license application contact Diana Tucker at Diana.Tucker@nps.ars, Office of Technology Transfer, Telephone: (301) 504-4878.^