Nylon Enamels is used as topcoat to improve lubricating and properties.
General purpose nylon enamel (aliphatic polyamide), mainly based on nylon 6.6, rich of cresylic acids. Low solid and high viscosity. Good lubrication. The enamel film is modified for higher melting point and better hardness.
The synthetic route using lactams (cyclic amides) was developed by Paul Schlack at IG Farben, leading to nylon 6, or polycaprolactam—formed by a ring-opening polymerization. The peptide bond within the caprolactam is broken with the exposed active groups on each side being incorporated into two new bonds as the monomer becomes part of the polymer backbone.
The 428 °F (220 °C) melting point of nylon 6 is lower than the 509 °F (265 °C) melting point of nylon 66.