I buy fusible interfacing by the yard using a JoAnns coupon, then cut it into long strips about 2 1/2 in wide, I butt the batting together then use a pressing cloth and steam iron and fuse the pieces together it works better for me than using the tape that is made for that... I put the interfacing on the back of the batting, that would be the smoother side.. pimples up, dimples down, that's how I tell the front from the back on the batting, then the interfacing that you use will be next to the backing and it won't show through, although mine never does anyway.