Hi, Viscose seems to be another name for rayon. When I sew with it, I always wash and sometimes dry it, but that's before I make something with it. The problem with rayon is that depending on the quality, sometimes it shrinks like crazy. I haven't actually had that problem with it for quite awhile (it seems to be better these days), but I'd be a little worried about that. It could be fine, though. I guess it depends on how much you love it. Also, if you do, rayon gets stiff when it gets wet, but softens up again once it dries (just so you know that's normal).