Normal day to day corrosion is a severe problem that affects any structure made out of steel and iron especially in India due to the extreme weather conditions. As paints have been misleadingly and increasingly been misunderstood for providing anti corrosive properties to any surface, people many times use the wrong paint on these structures. An oil-based paint is not an anti-corrosive paint and should be used only as a decorative paint which can only protect the structure partially. This becomes even more important when industrial structures are involved that use various chemicals and gases that are corrosive in nature.
A corrosion resistant coating will protect metal components against degradation due to moisture, oxidation, salt sprays if the building is close to the sea, or exposure from a multitude of environmental and industrial chemicals. These anticorrosive paints work by obstructing the corrosion by cutting the access of the metal to air, water and other chemicals. A wide variety of anti-corrosion coatings is available with anti corrosive paint suppliers which are mostly applied to iron or steel products.
Any paint is made up of three basic groups of items,
- A binder that holds the other components and sticks to the surface that has to be painted. It is usually a resin.
- A pigment which can be either organic or inorganic and provides the desired colour. Some of the pigments are also anti corrosive in nature.
- A solvent that reduces the viscosity of the binder and makes the paint flow for easy application.
The fourth category that many anti-corrosive paint manufacturers in India use is additives which are either liquids or solids and impart desirable properties to the paint. They can be catalysing and oxidation agents like metallic soaps or flow agents to help improve the flow of the paint or even surface agents like the ones used in preservatives. One such additive that can be added to paint is for improving its anti-corrosive properties though it is mainly controlled by using suitable binder and pigment.
To improve the quality of a binder it is important first to select the correct anti-corrosive pigment. Here are some combinations that most of the anti-corrosive paint suppliers in India stock. Epoxy is the most commonly used binder by anti-corrosive paint manufacturers in India followed by poly urethane resin with a few also utilising drying oils for such paints.
Selecting the correct pigment is not just for aesthetic properties but also to give the paint anti-corrosive properties. Red oxide is mainly used to provide this corrosion resistant layer. Some anti-corrosive paint suppliers also have aluminium powder and various chromates added to the paint that provides a metal like finish while providing an inhibitive layer to corrosion.
A prerequisite for the good performance of any anti corrosive paint is surface preparation which is also true for any type of paint. Using a clean surface devoid of any dust or grime and painting on a dry day will provide the best results. Painting is a composite system and the quality of the primer used, number of coatings as well as the finish all contribute to the anti-corrosive nature of the applied paint.