Epoxy resins are thermosetting polymers, which are crosslinked using hardeners (curing agents). Aliphatic, cycloaliphatic and aromatic amines are all employed as epoxy hardeners. Epoxy resins are typically cured by the use of additives, often called hardeners. There are also polyester resins cured by hardeners; however, the most common polyesters are thermoplastics. Polyfunctional primary amines form an important class of epoxy hardeners. This means that conventional nucleophilic hardeners such as amines are hardly suitable for crosslinking. In the studied system as hardeners must be used carboxylic acids or carboxylic acid anhydrides. Since many novolacs are solids, this class of hardeners is often employed for powder coatings. As part of the manufacturing process, the resin was mixed with hardeners and wax emulsion. It remains the main material for bullets, alloyed with other metals as hardeners. Its reactivity to hardeners is comparable to that of bisphenol A.