Hardeners are substances that are added to materials in order to increase their strength or durability. There are several synonyms for the word hardener, including curing agent, fixative, consolidant, and strengthening agent. Curing agents are typically used in the context of adhesives, coatings, and composites, and are designed to help these materials bond to surfaces and resist damage from wear and tear. Fixatives are often used in the context of paints and varnishes, and help to prevent them from cracking or peeling over time. Consolidants are typically used in the context of masonry and stone restoration, and are designed to increase the strength and durability of these materials. Strengthening agents are used to reinforce materials that are prone to breaking or cracking, such as concrete, steel, and plastics.