Place the article of clothing in a large plastic bag. Place the bag in your freezer and leave it overnight so that the compound may harden.
Remove the clothing from the bag. Wedge the blade of the butter knife between an edge of the hardened compound and the fabric. Turn the handle to begin prying up the compound from the fabric.
Scrape away as much of the compound from the fabric as possible. Work cautiously to avoid ripping or cutting the article of clothing. For very delicate garments, use a plastic butter knife to avoid damage.
Saturate an old rag with a solvent such as acetone or isopropyl alcohol. Dab any remaining compound with the rag. Brush away any small particles with a stiff brush.
Apply a prewash stain remover to the area. Launder the garment as normal.