When I used to work for an alterations shop, we would get in Levi's and such to shorten. The area where the flat-felled seam is consists of 4 layers of denim; make 1 roll, and now you have 8 layers; a 2nd roll produces 12 layers. That is tough going even for an industrial machine. The solution was to use a rubber mallet and pound that area into submission, protecting the fabric with another piece of cloth. I don't know if that might work for your situation or not. It might depend on if this is a wall hanging or a quilt too. The wall hanging doesn't care.