If you use a washaway, you'll have to adhere it to the fabric. There is a temporary spray glue that people use to adhere vilene to fabric like 505. They do have a sticky washaway that wouldn't require the spray glue, but I think it's expensive. There are a variety of washaways at this site.
http://www.worldweidner.com/Vilene-W...izer-12in.aspx