I am sewing on a thick denim like fabric. I am using a textile 40 nomex thread. I am using contrast colors, black on the top and tan in the bobbin. The problem I am having is that the black is showing on the bottom. I have changed my needles, played with the tension and I just can’t figure it out. I was hoping someone has run into this situation too.
I have included a picture to show what it looks like.