Anti corrosion coating prevents steel from rusting and deteriorating

Anti corrosion coating acts as a barrier between a metal and its environment, increasing its durability and lifespan. The estimated global cost of metal corrosion damage is billions of dollars. The good news is, a lot of this loss can be prevented by being proactive, and choosing the right anti rust coating from the start.

To determine the right anti corrosion 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 rust coating for steel and metal can help protect the substrate from the elements.

Corrosion categories and suitable anti rust coatings

To determine the right types of anti corrosive paints for your project, you need to understand the environment and use of the substrate. The corrosivity of certain atmospheres has been classified and standardised by the International Organisation for Standardization. The standard divides the degree of corrosivity into 5 categories , C1 to C5, in order of increasing corrosivity.

  • C1 – very low corrosion risk: Heated buildings with clean air, interiors only.
    Suitable for: offices, schools, hotels, shops and other heated premises.
  • C2 – low corrosion risk:  Unheated buildings, rural areas.
    Suitable for: storage facilities, sports halls, garages, barns and other unheated buildings.
  • C3 – moderate corrosion risk: Buildings with high humidity, urban and industrial areas.
    Suitable for: laundries, breweries, kitchens, food processing sites and other buildings with moderate humidity.
  • C4 – high corrosion risk: Chemical manufacturers and swimming baths, industrial and coastal areas.
    Suitable for: industrial buildings, chemical plants, swimming pools, ports, and ship- and boatyards.
  • C5 – very high corrosion risk: Buildings with almost permanent condensation, offshore and industrial areas.
    Suitable for: Water pipes and other industrial applications (C5I – industrial). Offshore and maritime constructions (C5M – marine).

Once you have identified your environment, you can identify the right anti rust treatment for your project and the right anti rust coating specification to protect it for years to come. 

Anti corrosion coatings for steel – the 3 types

Anti corrosion coating types can be divided into three categories:

  1. Inhibitor coatings (C1 – C4) – anti rust treatment which releases a chemical that 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.
  2. Galvanic coatings/Cathodic protection (C3 – C5) – metal-rich anti rust coating for steel 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.
  3. Barrier coatings (C1 – C3) – non-porous anti rust coatings designed to prevent corrosive factors coming into contact with the substrate.
    For example: powder coating, polyurethane paint, chloro rubber paints, Teflon coatings, nano coatings.

Types of corrosion and anti rust coatings to combat them

Corrosion in general refers to oxidation of metals, however, there are more than one type of corrosion. The following table outlines the most common types that can be combated with coatings, and the types of anti rust coating per corrosion type.

CORROSION TYPEEXPLANATIONAnti corrosion coating solution
General attackAlso called uniform attack corrosion, the most common form of corrosion. Hence the name. It causes the object to be entirely exposed to the rust.Barrier and inhibitor coatings, cathodic protection
GalvanicTriggered when two metals of different electrode potentials come in contact with each other in presence of an electrolyte such as saltwater. As a result metal ion flow from the more active material to the less active one speeding up the corroding of the more active metal.Barrier coating, cathodic protection
PittingOccurs when a hole forms in the metal. It occurs when a tiny part of the metal loses its protective layer, and becomes exposed to corrosive factors. May be difficult to detect because small size of the holes.Inhibitor coating, cathodic protection
CreviceSimilar to pitting corrosion. Because corrosion happens at a specific location.Minimising the tight spaces in design and applying barrier or inhibitor coatings or cathodic protection

Examples of anti corrosion coating products

Here is a selection of products on the market to give you a rough guide as to the price of anti corrosion paint. Keep in mind that for categories C4 and C5 it is not recommended to apply the anti corrosions coating yourself. Please search out a specialist in that case.

PRODUCTAnti corrosion coating TYPECorrosion Category
Jotun Jotamastic 90Barrier coating: Epoxy coating for above and below water, on concrete or steel, with abrasion and chemical resistance.C1 – C3
Jotun Barrier 90Inhibitor coating: Zinc-rich epoxy containing 90% zinc. Suitable for above water and on steel, with abrasion and water resistance.C1 – C4
Hempel GalvosilCathodic protection: two-component, solvent-borne, self-curing, inorganic zinc silicate with outstanding resistance against weathering and abrasion.C3 – C4
Hempel HempadurGalvanising coating: two-component, epoxy based. It cures to a flexible, well-adhering coating with good abrasion and impact resistance. Contains zinc phosphateC3 – C4
Ultrimax 1Inhibitor coating: Contains zinc phosphate anti-corrosive properties and a high volume of solids. C1 – C3

Anti corrosion coating manufacturers Hong Kong

Here Below you can find a selection of anti rust coating manufacturers operating in Hong Kong.

Anti corrosion coating manufacturerAddress
Jotun Paints (H.K.) Ltd.Room 902, 9th Fl.,101 King’s Road, North Point, Hong Kong
NCHUnit 1506, Peninsula Tower 538, Castle Peak Road, Cheung Sha Wan, Kowloon, Hong Kong”
AkzoNobel Hong KongRoom 2005, 148 Electric Road, North Point Hong Kong Island, Hong Kong S.A.R., China
Sika Hongkong Ltd.Rm. 1507, 15/F, Block A, New Trade Plaza, 6 On Ping Street, Shatin, N.T. Hong Kong.
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