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To Dye For

New method of dyeing cotton is less harmful to the environment, but the industry isn't interested, researcher says

FRIDAY, Nov. 23, 2001 (HealthDayNews) -- A method of dyeing cotton that employs positive and negative electrical charges uses significantly less energy, water and salt than traditional methods, making it more efficient and less harmful to the environment, says a textile scientist at North Carolina State University.

But the researcher says he's having a tough time getting the beleaguered U.S. textile industry interested in his work

The process, called cationic fiber modification, involves treating the cotton with a chemical, N-(3-chloro-2-hydroxypropyl) trimethylammonium chloride, which gives the cotton a positive charge to attract cotton dyes that have a negative charge.

The process takes about half the time of traditional cotton dyeing methods, two-thirds less energy, 80 percent less water and requires no salt, says Peter Hauser, associate professor of textile engineering, chemistry and science.

The traditional method of dyeing cotton uses water-soluble dyes, which don't naturally adhere well to cotton. That means large amounts of salt have to be added to make the dye less soluble and better able to adhere to the cotton.

And the amount of salt needed can equal the amount of fabric. That is, 1,000 pounds of salt for 1,000 pounds of fabric, Hauser says.

The traditional method also requires huge amounts of water. It takes eight gallons of water to dye one pound of fabric.

Cationic fiber modification isn't a new idea. It was developed in the 1970s but didn't generate much interest, Hauser says. About seven years ago, he decided to take another look at it and see if he could get the textile industry interested in the technology.

It seems it should be an easy sell. The electrical attraction means less dye is needed, the colors in the fabric appear more vivid, and there is no noticeable change in the texture of the cotton fiber. The process can be done using standard dyeing and finishing machines, so manufacturers don't even have to retool their operations, Hauser says.

The only drawback is that the fabric has to be taken out of the manufacturing line to be treated with the chemical. The fabric then needs time to react with the chemical. Hauser is focusing his research on overcoming that obstacle.

Despite all its advantages, Hauser says the textile industry doesn't seem excited about cationic fiber modification. He's run numerous trials in North and South America but has garnered only threadbare interest from textile manufacturers.

One reason may be that there aren't immediate, obvious financial benefits.

"This is more of a delayed type of thing. It's modifying the process that makes it more environmentally friendly and more productive, but it doesn't necessarily jump out at you as to what the monetary benefits are," Hauser says.

Attitude is another factor.

"You have to understand something about the textile industry. It's very conservative, very traditional," Hauser says.

That could change if a large clothing company wanted to promote a line of more environmentally friendly cotton clothing.

"It's much better if you've got a market pull rather than a technology push. We've got the best technology and the best way to do it, but until the marketplace demands it, the textile industry is really not going to change," Hauser says.

His research is partly funded by Dow Chemical Co., which manufactures the chemical that gives the cotton a positive charge.

Nolan Etters, a professor of textile sciences at the University of Georgia, calls Hauser's work "an interesting piece of research ... but I doubt very much that it will ever be utilized in a big way in this country."

The U.S. textile industry is in bad shape economically and it's doubtful, under such conditions, that any companies would take the time to adopt this process, Etters says.

What to Do: Here's a Web site about the U.S. textile industry and pollution. And here's one about the history of dyeing.

SOURCES: Interviews with Peter Hauser, Ph.D., associate professor of textile engineering, chemistry and science, North Carolina State University, Raleigh; Nolan Etters, Ph.D., professor of textile sciences, University of Georgia, Athens
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