I wonder if the Sulky wash away for machine embroidery would work ? Was it fused by an iron or just pressed on ?
Ericas has a bunch listed maybe see if any of these seem like what they were talking about , since I don't know what the project was or how they used it can't get anymore specific
http://www.ericas.com/applique/fusibles.htm
there is one called Wash Away Fusible Sheets that you fuse to the fabric sew it down - then it washes away ?