by Catherine Gianaro
Ah, the nature of cotton: the soft touch of a fresh bath towel,
the comfort of summer sheets, the gentle gauze covering a nasty wound.
But sometimes even nature needs a little help. Before it gains its tender
qualities, natural cotton must endure harsh chemicals to become absorbent.
That's why Ian Hardin is developing an alternative process that will
save time, energy and environmental injury.
"Most people look at the stains on clothing and just assume that cotton
is naturally absorbent," said Hardin, who heads the textiles, merchandising
and interiors department at the University of Georgia. "But if you take
cotton from a boll, remove the seeds and put it in water, it won't absorb a drop.
It will actually float there for weeks."
Cotton fibers have a waxy outer layer that must be dissolved through a process
called "scouring" before
liquids, such as dyes, can penetrate. Instead of using chemicals to remove
the waxy layer, Hardin turned to enzymes. He experimented with many - most
fruitfully with cellulase and pectinase - in sundry combinations. After each
attempt, he measured the amount of absorption.
"We need to find the truly optimum approach," he said. The goal is
to use the lowest concentration of enzyme for the least amount of time and at
the lowest temperature to achieve the desired degree of absorption. These three
variables - concentration, time and temperature - are the keys to the solution.
Temperature is a main concern because the chemical scouring process requires
high temperatures that demand more energy. "We can do it at a much lower
temperature [with enzymes]," Hardin said. "Knowing that, we can project
substantial energy savings."
Hardin's method also will cut the processing time by more than 90 percent. "Although
it varies with each mill, an hour is not atypical. And we're talking about
changing it to a matter of minutes," he said.
However, the new technique will require close management. "If you allow
these enzymes to continue working, they'll start eating away at the body of
the fiber," he said. "You have to maintain strict control of the
Environmental waste is another concern. The traditional scouring process
is performed with sodium hydroxide, often used in lye to clean drains.
It is extremely
corrosive in a concentrated form because of its high alkaline content. "By
itself, sodium hydroxide is not a problem, but combined with other chemicals
that are used in textile finishing and dyeing, it will increase the overall
inorganic chemical load in a plant's wastewater," Hardin said.
The new process leaves behind organic enzymes, which are proteins. "They're
made up of the same building blocks - essential amino acids - that your mother
said you had to eat when you were growing up," Hardin said. "These
enzymes are much more environmentally benign because they are natural, and
they easily degrade by natural processes."
But all textile waste - even enzymes - must be processed at a biological treatment
plant. Laws require that industries break down organic molecules before they
are released into streams.
"There'll always be some type of treatment because of what environmental
regulations require," Hardin said. "But the current water treatment
will handle the waste from the enzyme process as well. It'll probably cut down
on the environmental load overall, and you certainly won't be creating any more
Hardin's research is the first to suggest that enzymes could be used for
scouring; however, enzymes already have earned a healthy respect in some
of the textile industry. For example, one enzyme, a common protein called amylase,
has been used by the industry for 35 years to "desize," or break
down, the starch that is put on fabric prior to the weaving process.
On a loom, the yarns go back and forth through
the shuttle as many as 700 times a minute, generating a tremendous amount
of stress on the fabric. To lessen the amount of breakage and abrasion
during the weaving process and to lower the number of times the loom stops
due to broken thread, starch is used to strengthen the yarns. After the
fabric is woven, the starch must be stripped away before any further processing
Another enzyme, called cellulase, has been commonly used in the past five
years for "biostoning." Many manufacturers substituted enzymes
for the stones that were used to stone-wash fabric, such as denim jeans
that look like
they've been worn. Historically, this process was done by tumbling blue jeans
along with numerous pumice stones in a big laundry machine.
"Sometimes you actually had pieces of stones or grit in your pocket when
you bought new jeans," Hardin said. "Now most of the industry uses
Cellulase breaks down cellulose - the molecule that makes up the cotton
just eats away the surface of the fabric just like the stone would, but with
less damage to equipment. It also prevents leftover grit in the jeans and the
wastewater," Hardin said. "You can control your processes better
with enzymes than you could with stones."
Hardin's project is just one of nearly a dozen research areas that involve
the department faculty, many of whom also are involved in a state-wide consortium
to help the textile industry remain competitive in Georgia. The energy savings
coupled with the "environmentally friendly" waste in Hardin's new
scouring process make this desirable, cutting-edge technology, which is why
he has filed for patent protection.
Hardin has defined the essential ingredients - cellulase and pectinase
- and has established which parameters must be analyzed to optimize the
each industrial application. However, he continues to work on developing ideal
conditions for the specific materials. "I'm hoping that we'll get this
perfected within a year," he said.
Hardin also has the challenge of persuading industries to make the switch to
the enzymatic process.
"It will be a very fundamental change in the way [textile mills] do things.
We're asking them to change something that they've been doing for hundreds of
years," Hardin said. "But the industry will be able to switch without
investing in new machinery. If you were talking about them changing equipment,
that would definitely complicate the economics."
A New York textile company, Ajoy, already has expressed an interest in
Hardin's new scouring technique. The company markets a "natural" fabric,
usually adorned with black specks in a beige-colored material. These specks
motes, which are seed fragments that normally require further processing before
Hardin also has piqued the interest of the leading international enzyme companies,
the Denmark-based Novo Nordisk and the San Francisco-based Genencor. These
companies would mass produce the enzymes to sell to chemical suppliers, which
in turn would sell to textile plants.
Hardin's work is a breakthrough approach to improving the way fabric is made.
While that may not alter the nature of cotton, it could dramatically impact
textile manufacturing and make a major contribution to the $75 billion U.S.
For more information, access http://www.fcs.uga.edu/tmi/.
Catherine Gianaro is UGA's assistant director of research communications
and assistant editor of Research Reporter. She has a bachelor's degree
from the University of Florida College of Journalism and Mass Communication.