All of my patterns include paper pieced blocks, which are constructed with scraps of fabric going in various directions. It is important to quilt over the finished block so it will not stretch out of shape when laundered. But, after paper piecing a lovely image, it almost hurts to quilt over it! My go to method is to use invisible thread.
These 3 invisible threads are brands that I have used and I think they are all do a good job. Superior Threads makes MonoPoly, Aurifil makes a 100% Nylon variety, and YLI makes this Monofilament 100% Nylon Invisible Thread ...