Metal Coatings: The complete guide for industrial applications

Different types of metal coatings are naturally recommended for different types of purposes and industries. Let’s go through some of the most common purposes for metal coatings.

 

 

Corrosion protection

The main purpose of all types of metal coatings is simply to protect metal products from natural occurrences such as corrosion. 

Both water-borne and solvent-borne coatings work well in industrial use, but different types of coatings have different pros and cons. This means that before deciding on which coating to go with, you should always consider specific products and the specific use case at hand. 

There are many different metal coating methods for corrosion prevention, and due to their various features and qualities, each type performs differently and according to different parameters.

 

Better durability

In addition to protection from corrosion and natural elements, using quality metal coatings ensures better durability for the entire metal structure. 

Coatings that last longer also directly result in longer maintenance painting intervals, which in turn helps you manage costs in the long run.

 

Improved appearance

Metal coatings result in the long-term preservation of a structure’s cosmetic appearance, even under extreme conditions. With suitable and proper metal coatings, you can create a long-lasting finished surface with your preferred aesthetics including paint colour, gloss level, and more.

 

Increased chemical and water resistance

Applying a proper metal coating means forming a tough surface on your structure, and, in addition to protection from corrosion, the coatings are also highly resistant to any abrasion or chemical stress. 

If you need a metal coating for an environment of high humidity, it’s a good idea to consider solvent-borne coatings. To find out more about their differences and which ones you should consider for your structure, you can read our article on the differences of water-borne and solvent-borne coatings.

 

Fire protection

Certain metal coatings can also be used to protect the substrate from the effects of fire. Having a metal coating that protects from fire helps by giving additional time before the steel reaches a temperature at which it loses its load bearing capacity. This extra time allows evacuation of the building and a chance for the emergency services to control the fire. 

For example, one of our products — the Fontefire ST 61 — is a water-borne one-component intumescent coating that provides you with a heat expansion binding reaction that results in the creation of an insulating foam layer, which then protects your metal structure from reaching critical temperature for a certain period of time.

 

Additional functions

Some metal coatings serve other specific functions, such as preventing condensation. Our GrafoTherm line, for example, is a one-component water-borne anti-condensation coating for steel roofing sheets, steel structures and other metal surfaces, where condensation and dripping-water problems occur.

As another example, you might need high-performance, environmentally compliant solutions for the agricultural, construction, and earth-moving machinery and equipment (ACE) market. Our high-performance systems include water- and solvent-borne solutions that provide better protection while using fewer coats of paint.

Our solutions for different types of steel structures include coatings that protect against mild stress for interior surfaces, heavy stress for exterior surfaces, or even extreme chemical stress. We also offer a wide color range, including metallic colors that can also provide an aesthetic dimension.

Read our tips on steel structures painting.

There are many paint systems for maintenance and touch-up painting that are easy to use and do not need blast cleaning surface preparation. We also offer a system for surfaces immersed in water.

If you are not sure what kind of painting system or coating and surface treatment system you need for your specific metal structure, please feel free to contact us to find out more about your options.

As there are many different types of metal coatings, there are naturally multiple different factors to consider when choosing the right coating product for your specific needs. 

Your goals

To make the right choice, take the time to consider your goals with metal coatings. Ask yourself the following questions before making a decision: 

• What kind of painting conditions are we working with?
• What kind of environment is our end product used in? (Is it indoors? Or are there harsh weather conditions?)
• How long do we want the paint to hold? With some products, such as mining equipment, the paint is not expected to stay on the surface for longer than for the product’s first use. 
• What is our company’s mindset towards sustainability? You might choose to use water-borne coatings, for example, if your company’s long-term goal is to reduce your VOC emissions and the negative impact your operations have on the environment. 
• What demands are we currently facing? 
• Which painting system standards do we have to comply with?

Your processes

Consider the following questions about your current ways of working:

• What paints and coatings for metal surfaces are we using today? 
• What types of metal surfaces are we working with? 
• What equipment are we currently using? 
• Do we paint first and then assemble, or is it or other way around?  

The project timeline and deadline

Ask yourself the following questions when considering your project timeline:

• What drying time do we need?
• When are we able to pack the dried product? 
• How much should we be able to paint in one day?

Your budget and costs

Finally, consider your budget. Remember that some products require a higher initial investment, but pay off in the long term. For example, water-borne products are priced a bit higher because the raw materials to develop these products are priced higher. But after the initial investment of adjusting our equipment and processes, you start gaining back your investment. In fact, you can reduce your overall operations cost by using water-borne products. You don’t need to invest in explosion-proof equipment, highly flammable paint insurance, or specially trained personnel to transport the products because water-borne products aren’t flammable. Plus, wet water-borne paint can be cleaned with water, meaning you’ll save expenses by not using as many cleaning supplies. 

Additionally, using  DTM products rather than primers and topcoats will help reduce process time since only one application is needed. 

Remember that the cost of paint is just one part of the total project cost. The true cost of painting an object or unit takes into account all aspects of the treatment. And depending on what paint products you use, the total cost can be reduced by less dry film thickness (DFT), and shorter process time (application, drying). 

Use our cost calculator for metal products to better plan your budget.

This means, in short, that all systems need to be properly tested to these standards. 

The materials and systems we at Tikkurila supply comply with ISO 12944. Part 5 of this standard defines protective coating systems for different corrosive environments: C2, C3, C4, C5. The standard also determines durability ranges, which affects the time to the first major maintenance round: L, M, H and VH.

Tikkurila also has paint systems approved according to other standards as well. These include Norsok (Norway), Silko (Finland), GOST (Russia), and so forth. 

Part 5 of ISO 12944 defines protective coating systems for different corrosive environments: C2, C3, C4, and C5, and it also defines systems according to their ISO 12944 corrosion class. 

The standard also determines durability ranges, which affects the time to the first major maintenance round: L, M, H, and VH.

Next, let’s go through a couple of useful expert tips for working with metal coatings—from surface preparation to maintenance.

 

 

Metal coating equipment 

For different types of coatings, different equipment is required in order to allow the product to work its magic. 

For example, solvent-borne metal coatings require special explosion-proof equipment, as the products are highly flammable. In turn,  water-borne products aren’t flammable and don’t require such equipment. On the other hand, water-borne products still require equipment with stainless steel in all parts that are in contact with the wet water-borne paint.

Surface preparation

The success of your metal surface treatment largely depends on the surface to which it’s applied. Before applying the coating on your metal surface, the surface needs to be properly cleaned and roughened to ensure adhesion. The right level of cleanliness will help ensure the right performance of the coating. 

For instance, solvent-borne coatings are more forgiving of contaminated surfaces, while water-borne coatings always require a clean environment and surface—so, depending on which type of coating you are going with, ensure that the level of cleanliness is up to par with what the product requires. 

You can follow this example of a water-borne product’s recommended surface cleaning:

• Steel surfaces: Degrease and blast clean to grade Sa2½. (ISO 8501-1) If blast cleaning is not possible, phosphating is recommended for cold rolled steel to improve adhesion. 

• Primed surfaces: Oil, grease, salt, and dirt are removed from the surface by appropriate means. Repair any damage to the primer coat. Check your product's PDS for guidance regarding previously primed surfaces. 

 

Application

Your application methods could depend on several factors such as your equipment, the type of paint you’re using, production speed, output speed, and whether you’re applying on-site (at the painting shop) or off-site. 

Depending on these factors, you might use application robots, automatic painting lines, and different spraying techniques such as conventional, Airless, Airspray, and electrostatic spraying. For off-site maintenance and touch-ups, you might also use brush and roller application. No matter which method you use, correct paint application is key to get a long-lasting finish with metal coatings. 

Drying

If you are painting in very humid conditions, you might need to pay extra attention to drying. 

Especially with water-borne coatings, the water in the paint can’t evaporate properly in extremely humid conditions, and thus the paint will take longer to dry.

A possible solution for this is to apply metal coatings in a room where you can control the climate and keep the humidity at a certain percentage. The recommended humidity level is 20-70%.

In many cases you may fasten the drying time by increasing the temperature. The recommended temperatures depend on the paint. 

Maintenance 

The correct surface preparation and paint application will improve the coating’s performance lifetime, but some maintenance will most likely be needed after a period of time when working with metal coatings. 

There’s a wide selection of repair and maintenance products for industrial metal surfaces to choose from, and we at Tikkurila are of course available to answer any questions you may have. 

Chemical resistance

You might need metal coatings that require specific chemical resistance, such as oils, fuels, acids, and chemical solvents, among others. When considering metal coatings for a particular chemical environment, consider the following factors:

• Chemical exposure
• Operating temperature
• Mechanical abrasion
• Degree of protection required (immersion or splash/continuous or limited)