Fray check is a clear liquid seam sealant that is used to prevent fabric from fraying and to secure thread ends. It is washable and dry cleanable.
Sometimes the product can dry with a crunchy finish. Try this hack.
After applying Fray Check to the area you are wanting to stop fraying, (for instance, the end of a serged seam) and with the aid of a press cloth, press the area both front and back with your iron. Once the product is both cool and dry, then clip the excess threads. If you are using it on buttonholes, apply, press, then wait to cool and dry. Then slash your button holes with either a buttonhole cutter or seam ripper. The Fray Check will be seem non-existent.
Always try the product on a scrap piece of fabric first.