What is bias tape? Bias tape is used on quilts, necklines of shirts, hems of shirts, sleeves of shirts, an anywhere you don’t want to turn down a hem. Bias tape comes in all different types from very thick to very thin. Thick bias tape is what you used for quilts and blankets. Thin bias tape is used for shirts and things like that. whether you use thick or thin bias tape, it can be tough to put on, so be sure to pin carefully, sew slowly and be prepared to take out the stitches a few times.