"Greener" Jeans

Do you wear blue jeans? If so, you’re not alone! The sturdy pants are one of the most popular pieces of clothing of all time—and they have a long history. Denim, the material that jeans are made of, was first used for ship sails, tents, and wagon covers hundreds of years ago. People in California began making pants out of the fabric in the 1870s.

Today, most jeans are made in places outside the U.S. Unfortunately, the process of coloring them blue can come with a hidden cost. The chemicals that many jeans manufacturers use are toxic. If they spill into the environment, they can harm people and wildlife. 

Tammy Hsu is a scientist at the University of California, Berkeley. In 2015, she developed an environmentally friendly way to make jeans blue. Her process involves using a surprising ingredient: tiny organisms called bacteria. In 2019, Hsu founded a business to make blue jeans “green” around the world.

Do you wear blue jeans? If so, you’re not alone! These pants are one of the most popular pieces of clothing of all time. And they have a long history. Jeans are made from denim. The material was invented hundreds of years ago. It was used as fabric for ship sails, tents, and wagon covers. Then people in California began using the fabric to make pants. That was in the 1870s.

Today, most jeans are made outside the U.S. Creating their blue color often comes with a hidden cost. Jeans makers use chemicals to dye jeans. These substances can be toxic. 

Tammy Hsu is a scientist. She works at the University of California, Berkeley. She created a safer way to make jeans blue. Her surprising process relies on tiny creatures called bacteria. Hsu started a business in 2019. It aims to make blue jeans that are “greener.” That means they’re better for the environment.

The first makers of blue jeans dyed them with a natural pigment called indigo. This colored substance was made from indigo plants. But as jeans became more popular, there wasn’t enough natural indigo to dye all the pants. To keep up with the demand, scientists came up with a way to make a synthetic, or artificial, version of indigo out of other substances. 

“Synthetic indigo is very helpful,” says Hsu. “But it’s made and used in an unsustainable way.” Like natural indigo, synthetic indigo is not soluble. That means it can’t dissolve in water. This makes it difficult to dye jeans blue. 

To make the synthetic indigo soluble, manufacturers have to mix it with harsh chemicals (see Making Jeans Blue). Sometimes the chemicals used in the process spill or are dumped into lakes and streams. This pollution can make plants and animals sick. 

The first blue jeans were dyed with indigo. It’s a natural pigment. This colored substance was made from indigo plants. But jeans became more and more popular. There wasn’t enough natural indigo to dye them all. Scientists found a way to keep up with the demand. They made a version of indigo in the lab. It was synthetic, or artificial. 

“Synthetic indigo is very helpful,” says Hsu. “But it’s made and used in an unsustainable way.” That means it’s not good for the planet. Synthetic indigo is not soluble. It can’t mix into water. This makes it difficult to dye jeans blue. Jeans makers have to add harsh chemicals (see Making Jeans Blue). 

Sometimes the chemicals used in the process spill into waterways. Or they’re dumped into lakes and streams. This pollution can harm people, plants, and wildlife. 

Hsu and her business partner Michelle Zhu recently founded a company called Huue to produce indigo that won’t harm the environment. It uses the process Hsu invented in 2015. 

First, Hsu changes the DNA of bacteria called E. coli. DNA contains instructions for how an organism grows and acts. Hsu tweaks the instructions to tell the bacteria to produce a water-soluble form of indigo dye when the bacteria eat sugar. With a lot of sugar, the bacteria can make a lot of dye. 

Hsu and Zhu are planning to use the dye to make a prototype, or model, pair of jeans to test. They hope to soon work with jeans manufacturers around the world. Then jeans everywhere will be made in a more eco-friendly way.

Hsu teamed up with business partner Michelle Zhu. They recently created a company called Huue. It makes indigo that won’t hurt the environment. It uses the process Hsu invented.

First, Hsu changes the DNA of bacteria called E. coli. DNA contains instructions for how an organism grows and acts. Hsu tweaks the instructions. That tells the bacteria to make a water-soluble form of indigo dye. This happens whenever they eat sugar. The bacteria can make a lot of dye with a lot of sugar.

Hsu and Zhu will use the dye to make a prototype, a model pair of jeans they can test. They hope to soon work with jeans makers around the world. Then jeans everywhere will be made in a way that is more eco-friendly.