For infrastructure, machinery, and produced goods subjected to mechanical stress, chemical exposure, and hostile surroundings, industrial coatings are the first line of defence that is vital. Beyond appearance, these coatings are essential for maintaining the lifetime, safety, and performance of assets in sectors including oil and gas, automotive, marine, construction, and manufacturing.
However the actual efficiency of any coating system depends on its application and maintenance as much as its formulation. Achieving the best protection and performance depends on proper surface preparation, appropriate coatings application methods, and adherence to curing guidelines. Likewise, regular maintenance and inspection help coatings last much longer, so lowering long-term repair costs and downtime. Here are some of the best practices, challenges, and modern developments in the application and maintenance of industrial coatings.
What are the Application Methods Of Industrial Coatings?
Industrial coating processes are very important in safeguarding, improving and prolonging the service life of both manufactured goods and materials in all sorts of industries. The following are key methods of applying protective and decorative coatings:
Dip Coating
Dipping coating process
Dip coating is a simple and low-cost method for coating objects of almost any shape and size (including very large objects and objects with complex surfaces). This is done by immersing a part in a liquid coating such as resin, polymer or epoxy and slowly pulling it out. The coating thickness varies according to the duration of dipping, withdrawal speed, coating thickness and temperature and post-curing step.
E-Coat (Electrophoretic Painting)
E-Coat process Electrophoretic Painting
An E-coat is a paint application using electrical current that lays down a smooth and even layer of paint. The component is then immersed in a bath of water-based paint that is charged electrically, causing the charged paint particles to attach themselves firmly to the surface, including hard-to-reach corners and holes. Suppliers use multiple dipping techniques for this method to be invented, which provides perfect coverage, robust protection from rust, great resistance to corrosion, chemicals, and salt spray.
Brushing
Brushing coating
Brushing, as a hands-on approach, involves applying coatings with a brush perfect for small-scale applications, touch-ups, repairs or hard-to-reach locations, such as inside corners, welds or pipe fittings. Not sounding all that speedy, nor exceedingly sporty, however practical in its painstaking detail, or downsized tasking, if ever a high floor-price paint-coding feels in order. The kind of brush is important and has to be compatible with the material being coated. With brushing it might take several layers to achieve the required thickness, but it is cheap, quick to deploy and useful for on-site repairs or late design changes.
Roll Coating
Roller coating process
The Roll coating method is ideal when coatings need to be applied in uniform layers across large, flat surfaces such as metal sheets, plastics, or panels. Manual or fully automatic, making it suitable for large-scale production lines like coil or panel coating. Rollers spread the coating uniformly and have very fine control over thickness. Quick, efficient and involves no waste.
Spraying
Carry out the Paint Spraying Process
The application of coating with a spray gun or an automated system over a large or irregularly shaped part is referred to as spray coating. It’s multipurpose, fast, and effective on cars, steel beams, and electronics. Spraying offers the ability to get into hard-to-reach areas, and can be used for both thin paints and thick protective coatings. Some of these include adjusting the air quality and calibrating the equipment. Overspray and surface blemishes may occur, but experienced operators and solid process control yield a good surface finish.
Thermal Spray Coating
Thermal spraying is where you melt materials (metals, alloys, or ceramics) and then spray them onto a surface, forming a tough, protective layer. Common applications are for rebuilding worn components or improving their resistance to heat, corrosion or wear. Thermal spraying is common in heavy-duty application industries such as aerospace, power generation, and oil & gas and allows fabricating with a broad spectrum of materials with excellent bond strengths and coating strengths. Depending on the application and type of material, different techniques (plasma, flame, arc) may be more appropriate.
Spin Coating
Spin coating process
Spin coating is an electronics and laboratory process that uses a high-speed rotating disc to produce thin, uniform coatings on flat surfaces, such as glass wafers or chips. A thin film of liquid is placed in the center, then the object is spun at a high speed and the layer is evenly distributed by centrifugal force. It’s well-suited for ultra-wee films applicable in semiconductors or optics.
Flow Coating
Flow coating works well on flat or large horizontal parts that cannot be dipped, such as panels or glass. The liquid coating is applied to the surface in a controlled stream and does not require immersion. It’s low waste, speedy, and it can create thicker layers in one pass.
Slot Die Coating
Slot die coating is a very accurate method of coating thin and uniform layers of material onto a substrate, making it an important step in the production of many advanced products such as solar cells, batteries or flexible electronics. A slit is then used to apply the coating directly at the surface while the material to be coated slides underneath it.
Physical Vapour Deposition (PVD) Coating
Principle of Physical Vapor Deposition
PVD is a vacuum-based, high-tech process that applies atom-by-atom ultra-thin, durable coatings to surfaces. This is utilised in both decorative and functional coatings, enhancing hardness, wear-free nature, corrosion and/or smoothness. It is clean, environmentally friendly, and great for applications requiring high strength and a fine finish, with a variety of materials and colours used.
Industrial Coating Application Techniques – Comparison Table.
| Method | Principle | Advantages | Disadvantages | Application Scenarios |
|---|---|---|---|---|
| Dip Coating | Substrate immersed in liquid coating, then withdrawn and cured | Uniform coverage (internal & external), suitable for complex shapes, scalable | Coating runoff, excess use, drying/curing time | Automotive parts, electronics, aerospace components, corrosion-resistant tools |
| E-Coat | Electric current deposits charged paint from a water-based bath | Even film build, excellent for complex shapes, corrosion resistance, and environmentally efficient | Requires conductive substrates, expensive setup | Automotive chassis, appliances, HVAC, structural parts, pipelines |
| Brushing | Manual application using brushes | Low cost, targeted application, minimal waste, good for touch-ups | Labour-intensive, inconsistent thickness, slower for large areas | Maintenance, weld seams, bolts, irregular joints, and field repairs |
| Roll Coating | Coating transferred via rollers onto flat surfaces | High throughput, consistent film, energy-efficient, automated | Limited to flat surfaces, not for recessed parts | Sheet metal, architectural panels, appliances, and continuous manufacturing |
| Spraying (Air/Airless) | Coating atomised and sprayed via air or high pressure | Covers large, complex shapes; fast; versatile for various viscosities | Overspray, VOC emissions, and equipment maintenance | Structural steel, vehicles, machinery, architectural surfaces |
| Thermal Spray | Heated material (wire/powder) projected onto the surface at high velocity | High durability, wear/corrosion resistance, substrate flexibility | Expensive equipment, skilled operation required | Turbines, aerospace parts, mining tools, remanufactured machine components |
| Spin Coating | Coating spread by centrifugal force on spinning flat substrates | Ultrathin, uniform layers; precise; repeatable | For flat, small parts only; edge bead formation; sensitive to defects | Semiconductors, optics, MEMS devices, R&D applications |
| Flow Coating | Liquid coating flows over a stationary substrate | High efficiency for large panels, good coverage, and low waste | Limited to simple, horizontal shapes; may not suit 3D geometries | Glass panes, auto panels, sheet goods, architectural elements |
| Slot Die Coating | Pre-metered coating delivered through a narrow slot onto a moving substrate | Uniform, high-speed, scalable, supports multilayers | Complex setup; requires precise material control | Batteries, solar cells, flexible electronics, barrier films |
| PVD Coating | Vaporised material deposited in a vacuum chamber as a thin film | Ultra-durable, decorative, functional (wear, corrosion, conductivity); eco-friendly | High capital cost, vacuum environment required, limited thickness | Cutting tools, microelectronics, optical lenses, aerospace parts, cookware, medical implants |
Quality Control and Inspection of Industrial Coatings.
Quality control in industrial coatings is critical to ensure the longevity, functionality, and protective performance of a coating system. The process encompasses a series of rigorous inspections and tests that occur before, during, and after coating application. These steps are essential to verify that the coating adheres properly, meets design specifications, and performs under intended environmental conditions. Below is a comprehensive breakdown of key quality control points during and after the coating process.
Quality Control and Inspection of Industrial Coatings
Surface Preparation
The preparation of the substrate must be very thorough before any coating is added. This step is frequently seen as the most significant, as a coating will never perform as expected if it is not adhered to a properly prepared substrate.
The first is cleanliness. Clear away any oils, greases, salts and other impurities. Soluble salt testing (Bresle test, for example) is also used to determine the level of salts which may cause osmotic blistering if not removed. Visual cleanliness is examined according to ISO 8501, and standard reference pictures for acceptable surface states are referenced.
Another important area is the surface topography, more commonly known as the anchor profile. This roughness provides mechanical adhesion of the coating to the substrate. Surface paint profile testing includes readings obtained by replica tape, digital profilometers, or visual comparators. According to ASTM D4417, the profile depth must be within the range specified by the coating manufacturer, typically between 40 to 100 microns for many protective coatings.
It is also required that the environmental conditions are highly shiny on the stage. Surface temperature, air temperature, relative humidity, and dew point are monitored with calibrated devices. Coating of the surface should only be done when the surface temperature is 3°C above the dew point to avoid condensation of water, which affects adhesion of the paint.
Wet Film Thickness (During Coating Application)
Measuring wet film thickness (WFT) while applying paint can assist in achieving the specified dry film thickness. If the coating is too thin, it may not offer the necessary protective qualities, while if it is too thick, it may also be runny, sag, or not cure correctly. WFT is determined with a notched gauge or a comb directly after application. Such readings assist the applicator in modifying the spraying practice or coating weight at the time of treatment. The expected DFT is obtained by multiplying the WFT by the % by volume of solids of the coating. Thus, if the coating is 65% solids and WFT is 150 microns, then cured thickness will be around 98 microns.
FAQs
What are the applications of industrial coating?
Such coatings are often used to protect materials such as concrete and steel. In addition to that, industrial coatings also aid in improving the fire and other safety resistance of certain materials.
What is the application of coating material?
A coating material is used to cover the surface of an object and to enhance its life of the object. The purpose of applying the coating on the object’s surface is to decorate it and protect it from external factors, i.e. light, rain, cold, humidity, air, heat, etc.
