Corrosion resistant paint & coatings

Corrosion resistant paint and coatings protect metals from rusting

Corrosion resistant paint acts as a barrier between a metal and its environment, and increases its durability and lifespan. The roughly estimated global cost of metal corrosion damage is trillions of rupees. The good news is, a lot of this loss can be prevented by being proactive, and making the right choice of corrosion resistant coating from the start.

To determine the best corrosion resistant coating for your project, it is important to factor in the environment and type of metal. Whether corrosion is due to moisture, chemicals, salt spray, or oxidation, anti corrosion coating for steel and metal can help protect the substrate from the elements.

What all corrosion protection coatings have in common

Corrosion on steel can be prevented with corrosion resistant paint or coating.

Corrosion resistant paint is essentially a collective name for various types of coatings that protect a substrate from corrosion. A corrosion resistant coating can do more than just protect from corrosion, and its multi-functional nature means that it is possible to find the exact coating you require. Corrosion is caused by a chemical reaction between a metal and its environment (water or other fluids), typically producing an oxide or a salt of the original metal. The long and the short of it is the metal is weakened, as is the structure it creates. Corrosion protection coatings prevent direct contact between water/fluids and the steel substrate and therefore prevent the corrosion process.

In general corrosion resistant paint is suitable for almost any type of steel and metal, and has the following 5 benefits:

1. Water / fluid repellent or completely waterproof
2. Resistant to microorganisms such as fungi and algae
3. Weather protection against acid rain, UV radiation etc.
4. Chemical resistance, salt spray and other corrosive substances
5. Additional properties depending on the type of corrosion resistant paint you opt for: anti fouling, non slip or self cleaning etc.

The best anti rust coating meets the requirements of the corrosion category

To determine the best corrosion resistant paint for your project, you need to understand the environment and use of the substrate. Particularly its exposure to water, moisture, and other aggressive substances that might be present in the environment. The corrosivity of certain atmospheres has been classified and standardised by the International Organisation for Standardisation. The standard divides the degree of corrosivity into 5 categories , C1 to C5, in order of increasing corrosivity. To find the right corrosion resistant coating, you need to know how corrosive the environment will be. For example, a coating at C5M level is intended for offshore constructions which are constantly exposed to moisture, but also for small pipes that are equally exposed.

Once you have determined the corrosivity of your environment, you can identify the right coating systems for your project and the right anti corrosion coating specification to protect it for years to come. Following these guidelines will allow you to pick appropriate anti rust coatings, allowing you to avoid overspending on unnecessary degrees of protection or simply making the wrong choice.

3 types of corrosion protection coatings for industrial applications

Corrosion protection coatings can be divided into three categories:

1. BARRIER COATINGS (C1 – C3): non-porous coatings (corrosion resistant paint) designed to prevent corrosive factors coming into contact with the substrate.
   For example: powder coating, polyurethane paint, chloro rubber paints, Teflon coatings, nano coatings.
2. INHIBITOR COATINGS (C1 – C4) – release a chemical which interferes with the electrolyte and stops the corrosion process.
   For example: all oil based coatings with corrosion inhibitor additives such as zinc, aluminum, zinc oxide and so on.
3. CATHODIC PROTECTION & GALVANIC COATINGS (C3 – C5) – metal-rich coatings which provide a sacrificial layer. Prevents corrosion by providing a more easily corroded metal (such as zinc) to be the anode to the protected metal’s cathode. Also called the sacrificial anode, this metal will corrode instead of the protected metal.
   For example: hot dip galvanizing which provides steel (cathode) with a layer of zinc (anode).

Keep in mind that for categories C4 and C5 it is not recommended to apply the coating yourself. Please contact a specialist in that case.

DIp and spray applications of galvanic anti rust paint for metal

The two most common methods for applying an industrial grade anti corrosion coating for steel are hot dip galvanising and thermal (metal) spraying. Barrier coatings and corrosion inhibitor coatings can also be applied by spraying or dipping.

• HOT DIPPING (hot dip galvanising) is the process of immersing a metal in a bath of metal, often molten zinc,(or a polymer) in order to form a coating. The liquid metal bonds to the substrate and forms an alloy, which is then coated in zinc as it is removed from the bath. Hot dip galvanising uses the principle of cathodic protection, as the zinc coating acts as an anode to its substrate.
• THERMAL (METAL) SPRAYING applies zinc or aluminium to a substrate by taking the metal in the form of a powder or wire and feeding it into a special spray gun. The metal melts within the gun and can then be sprayed onto the substrate. It does not alloy, but instead works by coating the surface in overlapping metal platelets.

A duplex system forms the best corrosion resistant coating

When hot dip galvanising is used together with a top coat of corrosion protection coating or powder it is known as a Duplex System.

It provides multiple types of protection and the longest-lasting results. Each layer needs to be compatible in order for the system to work effectively. It is especially suitable for corrosion categories C3 to C5 and looks like this:

• Surface preparation including derusting, blasting, removing grease, oil, dirt for optimum adherence.
• Applying a primer either by hot dip galvanising or applying an inhibitor coating primer depending on the coating system of your choice.
• Applying a sealer to seal the corrosion resistant paint. Often epoxy based.
• Intermediate coat in several layer is necessary for optimum protection, depending on the corrosion category.
• Finishing coat to provide appearance and surface resistance, often first line of defence.

Protect smaller surfaces with anti rust paint for metal

For smaller substrates or do it yourself application up to category C2, painting at home is also an option. There are also small anti corrosion spray paint cans available for this purpose. An anti corrosion spray can be described as an ultra thin fluid film compound which you can spray on any steel or other metal surface. Such a spray can also function as a temporary anti rust coating for cars.

In spray form it can protect for up to a year. Keep in mind that more exposed areas which are getting constant abuse from rain and salt will need spraying regularly. In paint form, longer lasting results can be accomplished depending on the coating system you choose. For the best result always opt for a two component coating with corrosion inhibitor additives, for example a zinc rich epoxy coating.

Find corrosion protection coatings and manufacturers in India

If you are looking for a professional company to apply corrosion resistant coating for you, it’s important to understand how prices are established before you request a quote. Different coating processes use different methods to calculate the cost of professional application. Hot dip galvanising prices are usually calculated by weight. The galvaniser will quote a price per tonne, and then use the weight of your steelwork after galvanising to calculate the final cost. Unlike galvanising, powder coating prices tend to be calculated by size or surface area.

Regional differences in materials, labour, and equipment can all have an impact on overall costs when contracting a coating expert. If you want to receive a custom made quote, please contact us.

Here are a few examples of Indian corrosion resistant paint manufacturers accompanied by the address of their headquarters. In case you are looking for more detailed product information or applicators, do not hesitate to contact us. Out experts are here to help!