Iosso Seam Sealer protects against seam leakage without changing the look, color or feel of the fabric. The invisible sealer protects against water, soil and oil. Just apply to the seam and let dry. Seam Sealer is recommended for use on cotton, cotton blends, polyester and synthetic woven fabrics. Water repellency will vary with fabrics due to seam construction and threads used. The sealer is available in a 4-ounce applicator bottle and in larger professional sizes.