From the Quince & Co website:

Willet is our light and summery bird, sourced from high-quality, responsibly grown Cleaner Cotton™ (visit our blog to get the full scoop on this amazing fiber!). Possibly the softest cotton we’ve ever worked with, it is wonderfully springy and its long staple length gives it the barest hint of a pretty sheen. At 6 sts / inch, it works both as a sport and as a dk weight. In Willet’s crisp little stitches, we see the potential for sweet baby things, cool tanks and tees, pillowcases and summer throws, shawls…try it with a pretty lace or an etched knit/purl texture.

How to care for our cotton yarn:
Willet is machine washable, in some cases. Every machine is different, and we would recommend, if you are unsure about your machine, that you stick to hand-washing. If your machine can wash gentle and cool, then machine washing your piece will work just fine. Lay flat to dry.