i have quilted with cotton (breaks alot), poly, silk, wool(also breaks alot) and rayon threads all quilted up beautifully i think my machine behaves the best with the poly threads which is probably why she uses it exclusively. i have found my machines are all very particular about what threads they are going to allow me to use. if you like her work i would think it would be just fine to have her quilt your quilt. if you check out the web sites of some of the most famous quilters out there you will find most of them use poly's and rayon threads the most. because of the color options, shine, and usability of the threads. so far (i've been quilting for others for 7+ years now) i've never had any one worry about the fiber content of the thread i use. i don't think i've even had any one ask...other than once in awhile i get a request for invisible thread.