I recently finished a towel with embroidery on it and would like to secure the stitches with interfacing. Is the interfacing going to do the job? Or should I just sew a piece of fabric to the back?

I have read that interfacing will shrink when you wash it? Is this true?

http://www.dimensions-crafts.com/productcart/pc/viewPrd.asp?idcategory=9&idproduct=3659