I am afraid that it is too thick, and would interfere with the smooth movement of the fabric under the presser foot. The old-fashioned solution was to tape a business card over the feed dogs, but I've FMQ'd without covering the feed dogs, like Cari and Candace have. It wasn't easy, though - my mom's vintage Singer (mid-70's?) just doesn't have much room between the needle and the plate - could only do very thin blocks.