From the pattern:  "After a day of playing in the spring mud, this knit bath puff is perfect for a hot bath or soapy shower. It knits up quick enough to give as a sweet mother’s day gift, or to tuck into a spring holiday basket with a little bottle of shower gel.

If you substitute yarn, test a swatch to ensure colorfastness in hot, soapy water. And make sure it is a quick-drying material like nylon."