Knot a Problem knot sealer forms a clear, tough, flexible film on the bottom of lace bases to secure hair knots and prevent unwanted shedding. Knot a Problem dries fast to a clear, matte finish and will not return to a white, milky color, even when re-exposed to water. Our knot sealer will not damage or shrink delicate lace and does not contain harsh petroleum-based chemistry. We recommend two applications per use for the best performance.