Hello ... am crocheting a shawl in Promofil, a yarn that is 45% cotton, 35% viscose and 20% acrylic. It has a nice pearly sheen that shows well in half-double crochet, but I am wondering about its 'shelf-life' when it is made into a garment. In plain words, will it STRETCH with wear, or with washing? The instructions call for hand washing in warm water and laying flat to dry. Does anyone have experience with this yarn? Thanks!