Thread-Locking Compounds, Threadlockers are in the group Adhesives & Sealants. Adhesives, sealants, and adhesive tape can be used both at home, in construction, and in manufacturing. An adhesive is a glue-like substance used to firmly join items together. A sealant is a substance used to block the passage of fluid through a joint. Sealants may also have adhesive properties. Adhesive tapes are any one of a variety of backing materials coated with an adhesive compound.