Listen to part of a lecture in a fabric design class.

What are enzymes? You might still have a question about this after doing the assigned reading. Enzymes are really catalysts--chemicals used to get a reaction going. If you think about the human body, the human body's temperature is really not high enough to make reactions happen. So that's why there are enzymes to make certain reactions happen.

If you think about the digestive system, it has enzymes that help break down food. An enzyme in our saliva breaks down carbohydrates, sugars, and starches. And in the stomach and small intestine, we have enzymes that break down proteins and fats, in addition to carbohydrates. These enzymes are substances like lactase. You might have heard of that one. Lactase is the milk enzyme, and it breaks down lactose, the sugar in milk.

But today, let's look at the uses of enzymes in our industry. For instance, as I look around the room, I see many of you are wearing faded jeans. Do you know companies use enzymes to fade your jeans? They use an enzyme called cellulase to create that faded denim look, but we didn't always use cellulase. Well, we didn't always have faded jeans either. Back in the day when you bought your jeans, they were a nice, dark blue. It was only after many washings that they would get that faded look. It's only in the 1970s that companies realized there was a market for jeans that already looked faded. So companies started pre-washing their jeans.

Anyway, in the 1970s and 80s, pumice stones were used in a process called stone washing. What would happen? The textile companies would put pumice stones and oh, what is pumice stone? It's a volcanic stone. It's very light. It actually floats in water, but rough. And it's ground up and used in cleaning products like heavy duty hand soaps. So, these pumice stones would then, as I said, be put into a big washing machine and the jeans would be washed with these stones. Well, as you can imagine, when the process was finished, the washing machine was just about worn out. And the jeans would look faded, but also kind of worn out too, because the pumice stones would have abraded some areas more than other areas. Other things that would happen is the buttons on denim jackets or the rivets on the pockets would have a worn finish. But you want your buttons to be shiny and you want the rivets to look shiny too, right? Well, so that process didn't work very well.

There was another problem, but I'll get to that in a minute. Next, the textile industry moved to acid washing. They used acidic bleach, something stronger than you'd use at home. The bleach would break down the fibers and make the dye fade. You can imagine the damage here. Employees were exposed to acid, and it was not an environmentally safe process. The Environmental Protection Agency, a government agency, would monitor the wastewater that came from the company. And when they found this acid and the stones in a… yes, this is that other problem with stone washing I mentioned when they found these things in the wastewater that was not good because the agency would enforce anti-pollution laws and require the company to pay to clean up the water. So that added to the company's expenses and the cost of the jeans went up.

Finally, in 1989, the textile industry in Europe discovered what they called bio stone. That's the name they gave to the process of using cellulase is to fade denim. Cellulase is the enzyme that breaks down cellulose, just like lactase breaks down lactose. Jeans are made of denim, a type of cotton fabric, and cotton, being a plant, contains cellulose. And that's why they use cellulase. It's still a washing process just using cellulase instead of stones or acid. Using the cellulase creates more even and consistent finish on the denim without streaks or blotches, like you get in the other processes. And it's gentler. It doesn't wear out the denim that much. So you have a nice looking pair of pants that doesn't cost the company a lot of money to make. Also, cellulase treatments are less polluting than either stone washing or acid washing. At least according to manufacturers, another nice benefit. Don't you think?