Tips for using this new Simthread 30wt mercerized cotton thread: 1), this is 30WT thread which is thicker than normal 40WT sewing or embroidery thread, we recommend use needles with large eye (≥80/12) to prevent stripping in hand/machine sewing. 2), the cotton threads do not stretch a great deal like polyester or nylon threads, please slow down the stitching speed when you have breaking problem