Missouri Star Quilt Company cotton 50wt thread
I found this info: Missouri Star 50wt Double Mercerized Egyptian Cotton Thread made especially for use in both machine and hand quilting. This quality thread is double Mercerized to increase its strength and luster, which also allows the thread to absorb more color, infusing it with bright, colorfast dye that will last. Use it to quilt and sew a variety of fabrics. This versatile thread runs smoothly through your machine with a minimal amount of lint and it can withstand the rigors of washing, high temperature ironing, detergents, and mild abrasives. Let your projects shine in the sunlight without fear, it has excellent sunlight resistance too! Your memories are precious, so trust them to high quality thread at an excellent price.
https://www.missouriquiltco.com/shop/browse/6486?&Product_Type=MSQC%2BThread
I have been using the thread to piece and so far it's excellent.