The nice part about using indigo-dead jeans is that you automatically get a varied effect with dark blue on one side and the white on the back. The reason why indigo-dead fabric is like this is that this herbal natural dye does not sink into the fibers of the fabric like many other dyes, but only covers the outside of the fibers. Have you ever wondered why you have white-ish spots in jeans where they have most? This is because indigo is rubbed off and leaves the underlying color of the fabric being exposed, which – when it comes to jeans – is almost white.
As an interesting aside, "blue people" – the Tuareg nomads – … in northern Africa have blue skin where their indigo-killed clothes touch the skin. Tuareg is famous for wearing light blue clothes that died with indigo, and their process of not rinsing the dye causes the skin to turn blue from excess indigo color.
Anyway, back to the shagmat: you can make your shagmat completely out of jeans, but in this guide I chose to bring a light blue denim shirt and a soft, knitted white-blue striped sweater.