denim - blue is the best color

Denim is what jeans are made of. Everyone knows that, but what exactly is it that makes denim feel and look different from other 100% cotton fabrics?

Before we get into that, let's get something out of the way. Levi Strauss didn't invent denim. In 1853 he founded Levi Strauss in San Francisco, California to sell stuff. After a customer kept purchasing denim to repair pants, they started producing denim overalls in the 1870's (well after the California gold rush of 1849). The first pair of Levis 501 jeans were manufactured in the 1890's.

The name "denim" actually derives from the French serge de Nîmes which refers to the city in France from which Strauss imported the fabric.

Denim is a twill woven fabric with colored warp (usually blue) and white filling threads. This is part of the unique look. The mixture of two different thread colors gives it an overall different appearance. It is also usually all-cotton. (I don't know why Britannica puts a dash in all-cotton, but I included it here because it seemed so weird.) 

So, why do jeans feel different than shirts? Compare your 100% cotton T-shirt with your 100% cotton denim jeans. It's not too difficult to tear a hole in that shirt, but your jeans will probably stand up to a lot more punishment. They don't look or feel similar either. The shirt is smooth and flowing whereas the jeans probably have a stiffer rough feel.

The feel comes from the way the threads are organized. The primary weaves are the plain, twill, or satin weave. A plain weave is just a simple grid of threads.

plain weave

The twill weave forms a sort of diagonal pattern. The diagonal pattern makes stains a little less visible. It's also apparently more durable, although I was unable to figure out why that would be. I'm inclined to think it is similar to the way that a brick wall is stronger if the bricks are staggered rather than laid in a grid pattern. However, that's just my impression.

twill weave

Denim is a twill weave whereas a T-shirt is not woven at all. It apparently uses something called the jersey stitch which was originally used only to make underwear which caused quite the scandal at the time. However, when I hold my T-shirt up to the sun it looks a lot more like a plain weave than a jersey stitch to me.