Jeans are often referred to by their colour. We call them “blue jeans.”
But did you know that the blue colour in blue jeans has been used to dye clothes for thousands of years? And have you noticed how the colour changes as you wear and wash your jeans?
It’s called ‘fading’—and it’s because of the way denim is dyed that it happens. In this lesson, you’ll learn how denim is dyed.
Dyeing is the process of adding colour to the yarn. It’s done by soaking the yarn—or a woven fabric—in a liquid that contains a dyestuff.
The classic kind of denim that is blue on the outside and white on the inside is ‘yarn dyed’—only the warp yarn is dyed while the weft is left natural or bleached. For solid colour denim, fabric dyeing is often used.
The blue dyestuff in blue jeans, indigo, originates from India. “Indigo” literally means “a substance from India.”
You can learn much more about the history of indigo in this blog post.
Indigo is a vat dye. To get the dyestuff onto the yarn or the fabric, it’s solubilised in water with the help of a reducing agent.
When the yarn or fabric is pulled out of the dyeing vat, and gets in contact with the atmospheric oxygen, the oxidation process binds the colour molecules to the fibres of the yarn.
The reason denim fades is the modern dyeing process. It gives what’s known as a ‘ring dye effect.’ The colour doesn’t reach the core of the yarn. The dyestuff only binds externally. As the dye slowly wears and washes off, the undyed core appears.
When you buy a pair of raw denim jeans, there’s still have some starch left in fabric from the sizing process. Combined with the tightness of the weave, this is what gives raw denim its stiffness.
In the in-depth member resource about indigo dyeing, you can learn more about the types of dyes used for denim and two dyeing methods.
How to Use This Knowledge
When you’re selling jeans, you probably get questions about why they fade and how the colour will change. Knowledge about how denim is dyed and why it fades helps you answer such questions.
And that enables you to better guide your customers about what to expect in terms of how (the look of) their jeans changes with wear and wash, which can prevent complaints and returns.
Just keep your explanation simple, like in the video above.
Get access to more denim knowledge with a FREE member account
In the member resource and the lesson about how denim is dyed in the Denim 101 course, I go into more detail about the pros and cons of washing your jeans one way or the other. To get access, you first need a member account.
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