If you are talking about "Maxilock", it is not a thread that was made to hold up to seaming or quilting. It was designed to be a cheap and light thread for finishing the cut edges of garments, to keep them from raveling. It sounds like people have gotten away with using it on their quilts, but if you want your quilts to last a lifetime, I wouldn't use it. I made all my kid's clothes when they were small, using a serger and knit fabrics as much as possible (faster, easier). It was then that I learned the serged seams with Maxilock do not hold up. The thread will break easily in any kind of stretchy seam under stress. I know quilt seams are not stretchy, but a thread salesman confirmed my findings that Maxilock is a lightweight thread. I would use at least a Tex 40 rated thread for quilts. Maxilock is only a Tex 27.