For the Strongest, “No-Sew” Bond. HeatnBond Ultrahold iron-on adhesive is perfect for no-sew crafting, home decor and applique projects. Ultrahold has 3 times more adhesive than traditional fusible webs and provides the strongest bond available of any iron-on adhesive. It is acid-free, non toxic. Use with fabric, foil, lamé, denim, felt, suede, leather, wood, cardboard and more. Machine washable, for best results, use a delicate cycle and lukewarm water.