These were optional exercises for chapter 10. I almost didn't do them because they were about burning synthetic fabric. In the past, I loved using this technique, but never really paid strict attention to the warning and safety precautions which has caused some health issues. I decided this was a bad excuse and it was time to work with a quality respirator!
It was hard to get down to the cotton bottom layer. It was useful to remove the top layer of synthetic fabric to leave the next layer, but hard to control and stop it from going too many layers.