4. Top coats

The application of an additional film to a chromating layer is a technique that has been well known to applicators for some fifteen years, not only to protect the chromating layer from thermal shock, but also to impart sliding properties, particularly for screw applications. These products are known as top-coats or organo-mineral finishes, or sealer, a term which clearly illustrates the product's function, which is to "seal" the chromating layer more or less hermetically.

The aim of this paragraph is not to provide an exhaustive review of these processes, but to highlight their importance in the approach to an overall system for protecting electro-galvanized parts.

These products can be broadly divided into two categories: water-based mineral finishes, and water-based organo-mineral finishes.