How Could Blue Denim Be Greener?

It takes a lot of water and some toxic chemicals to dye our denim blue. Learn how research into chitosan could make the process more environmentally friendly in this episode of BrainStuff, based on this article: https://science.howstuffworks.com/environmental/green-tech/sustainable/denim-dyeing.htm

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Episode Transcript

Speaker 1 (00:01):
Welcome to brainstuffe A production of iHeart Radio, Hey brain stuff,
Lauren bobabam here. Whatever color your clothes are, the process
to make them that way is probably pretty toxic. According
to the United Nations Environment Assembly, textile dying is the
second largest water polluter in the world, and not only

(00:23):
is the dyeing process rife with harmful chemicals, it's very
water intensive. Your average pair of jeans takes up to
twenty six gallons. That's a hundred liters of water to
die in. These days of fast fashion, our hunger for
trendy clothes is directly harming us and a lot of
other organisms and ecosystems all over the world. The denim

(00:45):
industry alone uses over forty five thousand tons of synthetic
indigo a year, more than eighty four thousand tons of
sodium hydro sulfite and fifty three thousand tons of lie.
According to scientists at the University of Georgia, this adds
up to a big environmental problem. However, a research team
at that university has worked out a solution that eliminates

(01:06):
noxious chemicals from the denim dyeing process while using a
fraction of the water, but let's back up a step back.
In the seventeen hundreds, indigo, the plant that historically gave
denim that iconic blue color, was a major export of
the American colonies. These days, however, we die our blue
jeans with synthetic indigo pigment, which is why you can

(01:28):
buy a pair of jeans for fifteen bucks. But no
matter whether the indigo is natural or synthetic, the process
of dying denom requires a strong reducing agent to make
the dye dissolve in water. For the article of this
episode is based on how Stuff Works. Spoke with Sergei Minko,
a co author of the study and a professor in
the College of Family and Consumer Sciences at the University

(01:50):
of Georgia. He said, the commercial technology for dyeing textiles
uses aggressive chemicals. For denim, a strong toxic reducing agent,
old sodium hydrosulfite is used to make it soluble. Some
amount of this reducing agent is used in each stage
of a repeating process anywhere from five to ten times
if they want to get an intense shade. And as

(02:15):
we said, this process uses a huge amount of water.
A pair of genes can take up to two thousand
gallons to produce, and that's about once you consider the
water it takes to grow the cotton, dye the fabric,
and manufacture the pants. Not only that, but many of
the chemicals involved in denim dyeing don't degrade in the environment.

(02:36):
While the technology does exist to filter the toxic chemicals
out of the water before it hits a river or
a stream, many of the places in the world where
garment production happens at China and Bangladesh, for instance, don't
require the infrastructure to remove the chemicals from the water
before it contaminates waterways and ends up poisoning wildlife people
in crops. Minko said. Some of the environments where they

(02:59):
die text ills, everything is artificially colored in different shades.
Of course, the major damage doesn't come from the dyes themselves,
but high salt concentrations and these reducing agents, which can
be very aggressive in ecosystems. So let's talk about the
new denom dying method that the researchers came up with.

(03:20):
This process mixes cellulose nanoparticles called kitisen that are made
from wood pulp with natural indigo dye. Although the researchers
believe synthetic dies could also be used. This mixture creates
a sort of gel that can be applied to the
fabric a single time to yield an intense indigo color,
compared with the multiple dip process of conventional dyeing that

(03:41):
requires up to ten applications of dye to yield a
dark shade. The kitisen essentially glues the pigment in place
after the fabric dries, creating a sort of matrix of
dye that coats the fibers of the denom. Because this
process doesn't involve dissolving the indigo dye, and no reducing
agents are necessary, thus cutting the amount of water used

(04:02):
in conventional dyeing methods by about nine Not only that,
but the process is non toxic, the drying time for
the kitis and dye is shorter, and the new technique
yields fabric of the same weight, thickness, and overall feel
as traditionally died denim. Here's hoping that more research can
bring this new fabric technology out of the lab and

(04:24):
into practice. Today's episode is based on the article A
New Green Solution for dyeing blue denim on how to
works dot Com, written by Jesslin Shields. Brain Stuff is
production of iHeart Radio in partnership with how stuff works
dot com, and it's produced by Tyler Klang. For more
podcasts my heart Radio, visit the iHeart Radio app, Apple Podcasts,

(04:46):
or wherever you listen to your favorite shows.