You could buy a small quantity, swatch, and launder by machine, but it seems a lot of trouble to me. I can endorse the 100% acrylic I bought from them. I’ve used it before for charity hats and scarves, and it came out of the washer and dryer perfect.
I may have to do that. The afghans will require a significant amount of yarn, and it is on sale now, but I don't want to buy a quantity sufficient for 6 afghans and have it not be suitable.
I've also used their acrylic for baby items. I really liked the long striping colors and the items turned out really well. For these afghans, though, I need a heavier weight yarn. And it would probably be nice to have a wool/acrylic blend.