You should not use coated quilting cotton in your machine. The coating will interfere with the tension discs of your machine and gunk them up. Use the coated cotton for hand quilting. It is made that way to slide easily whilst you are hand quilting. Mettler brand quilting cotton is OK to use in the machine, as it doesn't have the coating, but you have to check which Gutterman thread you are using. it is usually marked as hand or machine quilting cotton. Most brands differentiate in this way so that you don't use the wrong one.