I have strip sets that are bowing from being sewn. I have a Steady Betty ordered and can't wait to get it. I was wondering if it would be okay to mark some gridlines on it? Not sure what the surface is and if the pen would come off on the fabric (would a sharpie transfer from the surface to fabric after it has had a chance to dry overnight)?. If anyone has experience with this and could let me know if it works okay that would be appreciated.