I mix just about everything and anything that's cotton or mostly cotton, and have never had issues. The quilt police never come to my house, so I haven't worried about it. If I like it, I use it! I watched a youtube video just a few days ago by a gal who uses wool, silk, cottons, any natural fibers of all weights to make her quilts. They were beautiful and she had some tips for working with the different wights of fabrics. I can't seem to find it or I would post a link. If I find it I will try to remember and come back to post it.