In a recent tutorial you might have seen that I had a red sandpaper in the photos when I was marking my half square triangles (HST) or other bias line marking.
In May I went to the Original Sewing Expo and one of the classes I took listed sandpaper as a material we needed to bring. I was a bit mind boggled by this but after a quick stop by the hardware store to pick up some fine sand paper I made my way to to expo and the class.
The instructor explained that the sandpaper helps keep the fabric in place as you mark lines that would usually cause the fabric to stretch, shift or cause your lines to not be as straight.
Such a very clever trick especially when using a marking device that tugs the fabric as you write.