Knowledge Center

A primer undercoat creates a chemical bond producing strong adhesion between the substrate and the coating. It also ensures durable protection against corrosion should the coating be damaged. Priming ensures better adhesion of paint to the surface, increases paint durability, and provides additional protection for the material being painted. Some products contain an adhesion promoter in their formulation, enabling to apply directly on metal without using a primer. The choice of these solutions depends on the final use conditions. In all cases, if in doubt, do contact us for an advice.

Coatings should be applied over clean substrates. Normal industrial practices, such as chemical washes or solvent cleaning and degreasing can be used, but precautions must be taken to remove all residues from the cleaning process.

Preheating metal substrates is advantageous in removing traces of oil and other contaminants, especially when the metal is cast and somewhat porous.

Depending on the initial condition of the metal, it may be necessary to physically remove dirt, rust, mill scale, paint, etc. Grit blasting is the method most commonly used to obtain good adhesion. other methods of surface roughening are employed in special cases. Wheel sanding, wire brushing and directional grinding may be used where best adhesion is not required. However, these operations reduce adhesion in the direction of the grind.

Cleaning by grit blasting, sandpaper, steel wool or No.400 emery cloth is much better than any chemical etching such as chromic acid, hydrochloric acid, or sulphuric acid.

Conversion coatings are the modified surfaces of metal resulting from specific chemical treatment. These conversion coatings, which can be on steel, aluminium or most other metals, typically include zinc, manganese and iron phosphates or chromates.
The principle function of these coatings is to improve adhesion of finishes and to maximise corrosion resistance. The functionality of conversion coatings depends upon their uniformity and the integrity of the coating, both before and after application of the final finish.

For more information, read our application guide

The paints and coatings industry is increasingly eager to develop sustainable product offerings to reduce environmental pollution. As such, Tetrachim is constantly looking for efficient bio-based materials. As such, Rilsan® polyamide resin is produced from castor oil obtained from the widely cultivated Ricinus communis. Castor oil is 100% vegetable, biodegradable, natural, non-toxic and renewable. Being environmentally sound, Rilsan® Fine Powder is  the right product for customers in search of eco-design. In addition, Rilsan® polyamide resins require less non-renewable energy than most performance polymers and offer a responsible choice for the environmentally aware.

Go to our bio-based product selection