Stainless steel coating protects and preserves the steel, as well as maintaining its aesthetic

Stainless steel coating protects and preserves

Stainless steel has been relied on for everything from scalpels to skyscrapers for decades now; its corrosion resistant formulation, versatility, durability, and tensile strength make it an ideal material across a range of industries. Its most prominent use is in construction, and Australia is no exception – projects using stainless steel in their production include Adelaide Airport, the Australian Museum in Sydney, the Victorian College of Arts, and, of course, Parliament House in Canberra, where the flag flies from a flagpole made from 200 tonnes of Newcastle stainless steel. Although it is called “stainless steel” there are various ways the material is treated in order to extend its life and protect it, especially in harsher conditions. Stainless steel coating is one of these methods.

In this article we look at stainless steel coating including powder coating, epoxy coating, coil coating, and invisible nano coating for easy-to-clean interior surfaces. We also look at stainless steel coating suppliers and services in Australia.

Why you need stainless steel protective coating

Stainless steel is so called because of its heightened resistance to corrosion and discolouring. This is because of the way stainless steel is formulated – it is an alloy of iron with a minimum of 10.5% chromium. Chromium produces a thin layer of oxide on the surface of steel which which the underlying metal from the effects of the environment, including corrosion. The higher the percentage of chromium the more corrosion resistance the steel has. However, certain conditions, environments, and end uses will have differing levels of harshness and will require more intense protection.

Whether it is strong sun, strong rain, high humidity, cold, or salty coastal and offshore winds and environs, outdoor structures in Australia can suffer a great deal of abuse. Coating for steel protects and preserves steel while also adding a decorative appearance. Whether the steel needs fire protection, corrosion protection, heat protection, abrasion resistance, or a specific finish, there is a right coating for the job. Carefully selecting a stainless steel coating is important due to the fact that it must provide sufficient durability and meet the requirements of the service environment. The combination of surface preparation and formulation of the paint system are key factors in meeting these objectives.


Choosing the right method for painting stainless steel

Choosing the right stainless steel coating will depend on a combination of the substrate (type 304, 316, etc), the condition of the steel, the environment in which the steel will be used, and the intended purpose of the steel. Below is a list of the most common technologies for painting stainless steel, and a table outlining the various stronger corrosion environment and the appropriate liquid coating systems for each.

First things first – surface preparation

In general, stainless steel has flatter and smoother surface than carbon steels and this can cause problems with coating. This applies particularly to sheet and coil products and may adversely affect adhesion between the metal surface and the coating system. Roughening of stainless steel surfaces prior to coating is essential; abrasive blasting, light hand abrasion or chemical etching are common ways of achieving a rougher surface. Prior to coating, all stainless steel surfaces must be dry and free from rust, other foreign materials, oil and grease. The presence of such contaminants may lead to failure of the coating system. The compatibility of any existing coating and the new stainless steel coating is important; incompatible systems may lead to flow problems, discolouring or leaching.

1. Powder coating stainless steel

Powder coating is a process where paint in the form of a dry powder is applied to a substrate through static forces and hen baked, causing the powder to melt and flow across the surface. By applying powder coating to stainless steel you are providing extra corrosion resistance, UV stability, abrasion resistance, and extending its lifespan. Powder coating also has the benefit of being more environmentally friendly than other coating types as it requires no solvent and so releases no VOCs. Powder coating is also a highly attractive finish with a range of colours and effects available.

2. Coil coating

Coil coating for steel is a continuous process which starts with an untreated coil of metal sheet that is unwound, treated, coated, cured, rewound, and packaged for shipment at a rate of 100-200 metres per minute. This process can be for one or both sides of the metal sheet, and can apply and cure up to three layers of paint. Coil coating commonly uses polyester, polyvinylidene fluoride (PVFD),  epoxy, polyurethane, fluoropolymer, and silicone-modified polyester. Coil coating reduces costs and reduces waste while providing a high quality finish and corrosion resistance. It is highly utilised in the architectural and construction industry.

3. Nano coating  – invisible protection

The durable, corrosion resistant, chemical resistant, and hygienic nature of stainless steel means it has found use in hospitals, household appliances, food preparation spaces and more. To keep the stainless steel appearance while increasing its resistance, ease of cleaning, and maintenance, clear coating can be applied. These coatings make use of nanotechnology to provide a nanoscopic waterproof layer that also makes them smudge and fingerprint-proof.

4. Liquid coating – epoxy, polyurethane, and more

When painting stainless steel it is crucial to ensure good adhesion between the coating and the substrate. It is usually advisable to roughen the surface before applying the paint through pickling or abrasive blasting. A protective coating for stainless steel is usually required because of extreme or harsh conditions, such as tank linings or offshore platforms. One of the most common systems involves an epoxy base coat and polyurethane top coat.

The table below gives details of paint systems suitable for coating stainless steels and, in accordance with ISO 12944 and ISO 9223, classifies them in terms of the severity of the envisaged service environment.

Corrosion Category Corrosion Risk Location Stainless steel coating system example
C3 Medium Rural and urban areas with low sulphur dioxide, acid, alkali and salt pollution Two pack epoxy or polyurethane steel primer paint at 30-50 micron dry, followed by high solids polyurethane finish at 100 micron dry
C4 High Urban and industrial areas with moderate sulphur dioxide and/or coastal areas with low salinity Two pack epoxy or polyurethane primer at 30-50 micron dry, followed by high build epoxy at 100 mm dry, followed by re-coatable polyurethane finish at 60 micron dry
C5I Very High Industrial areas with high humidity and aggressive atmospheres Two pack epoxy or polyurethane primer at 30-50 micron dry, followed by high build epoxy at 200 micron dry (one or two coats), followed by re-coatable polyurethane finish at 60 micron dry
C5M Very High Coastal and offshore areas with high salinity Two pack epoxy or polyurethane primer at 30-50 micron dry, followed by high build epoxy at 200 micron dry (one or two coats), followed by re-coatable polyurethane finish at 60 micron dry

Stainless steel coating manufacturers and suppliers in Australia

There are stainless steel coating companies and businesses operating Australia-wide, from Perth to Sydney. Once you know what you want from your coating, you can narrow down the kind of coating and the business that you need. Make sure any contractor you hire adheres to the Australian and New Zealand Standards. Below is a list of just a few of the businesses and the services they offer.

If you want more information about stainless steel coating, or have a project that you need coating for, get in touch! Our experts are here to help. Simply use the “Request a Quote” button beneath this article and tell us a little about your project to get things started. Our quotation service is 100% free, so contact us today and let us, in collaboration with our coating partners, connect you with the right coating for your needs.

Stainless Steel Coating CompanyLocationStainless Steel Coating Services
EnduroShieldNSW / ACT/ QLD / NT / VIC / SA / TAS / WAAn invisible, non-stick protective treatment for stainless steel that makes it easy to clean and maintain. For kitchens, worktops, sinks, barbecues, fridges and more
Global PumpsAustralia-wideMetaline elastomeric protective coatings to protect from wear, water, chemicals, corrosion, and more.
Jet-Hot Coatings AustraliaCastlemaine, VictoriaA variety of coatings for insulation, corrosion resistance, abrasion and impact resistance, and lubricity.
NanokotePerth, Western AustraliaA clear coating service that protects stainless steel from chemicals, corrosion, abrasion, fingerprints, tea staining and more.
Quality Powder CoatingBayswater, VictoriaPowder coating and abrasive blasting services for a range of substrates.