Industrial painting includes different techniques used to apply paints, coatings and functional coatings to surfaces. The choice of application method depends not only on the product used, but also on the geometry of the component, the viscosity of the formulation, the required thickness, production volumes and the level of control needed during application. Brush application, spraying, dipping, flow coating and powder coating all meet different requirements. Not every technique is suitable for every product and, particularly when technical coatings for metal processing are used, the application instructions for the specific formulation must be taken into account.
ATP Europe develops coatings and technical solutions for a wide range of industrial processes. In this guide, we explore the main types of industrial painting, explaining how they work and which factors should be considered when selecting the most suitable application method.
What is industrial painting?
The term industrial painting refers to the range of techniques used to distribute a product over a surface under controlled and repeatable conditions. Unlike a purely manual or decorative application, in industrial processes the method used must be compatible with the characteristics of the coating and with the production objectives. The coating may perform an aesthetic, protective or strictly technical function. In the metallurgical industry, for example, products can be applied to protect materials at high temperatures, mask selected areas during a treatment, facilitate processing or enable component marking.
The different functions of coatings are explored in our guide to industrial paints for metals. On this page, however, we focus specifically on how the product can be distributed over the surface.
How to choose an industrial painting method
There is no single application system that is universally better than the others. The choice must begin with the characteristics of the component and the product being used. The main factors to consider include:
- component geometry and dimensions, since complex shapes, cavities and large surfaces may require different techniques;
- product viscosity, which influences coating distribution and compatibility with the application system;
- required thickness and the level of uniformity needed;
- number of components to be treated and the level of process automation;
- areas to be coated, distinguishing between complete coverage and selective application;
- conditions following application, such as drying, heating or possible polymerisation.
The initial preparation of the component can also affect the result. Cleaning, surface condition and correct product preparation are discussed in more detail on the page dedicated to the complete metal painting process.
Industrial brush painting
Brush painting is one of the simplest application systems and allows the operator to distribute the product manually over the surface to be treated. The main advantage is direct control over the application. A brush can be particularly useful when the coating needs to be applied to limited areas, when small quantities of components are being treated or when the geometry of the part makes manual application more practical. This characteristic can also be particularly important when applying functional coatings that require selective masking: in certain processes, only specific areas of the component may need to be coated.
The result, however, depends on correct product distribution. Excessive quantities, uneven strokes or unsuitable viscosity can lead to differences in thickness. Even a seemingly simple technique therefore requires the application conditions specified for the formulation to be followed.
Industrial spray painting
Industrial spray painting distributes the product through a system that atomises it and deposits it on the surface in the form of particles or droplets. Compared with manual application, spraying makes it possible to treat larger surfaces more quickly and, when the parameters are properly controlled, achieve a uniform distribution of the coating. The result depends on several factors: equipment type, nozzle characteristics, pressure, distance from the component, application speed and paint viscosity must all be compatible with one another.
Spray painting should not be confused with flow coating. In the first case, the product is atomised before reaching the surface; in the second, it is distributed as a liquid flow without being atomised.
Industrial dip painting
Dip painting involves placing the component directly into a tank containing the liquid product. During immersion, the coating comes into contact with the different surfaces of the part. The component is then removed and the excess product is allowed to drain before any drying or treatment stages required by the process. This method can be useful when extensive coverage of the component is required, including surfaces that are difficult to reach manually. However, component geometry, immersion and withdrawal speed, viscosity and drainage directly affect the final distribution.
An excessively viscous formulation, for example, may cause build-up in lower areas or in more complex geometries. The orientation of the component must also be considered to allow excess product to drain correctly.
Flow coating and curtain application
Flow coating uses a different principle from spray painting. The liquid product is distributed over the component through one or more continuous flows, without being atomised into small droplets. The coating flows across the surface of the part, while excess material can be collected and recirculated within the system. This makes it possible to treat complex surfaces by appropriately adjusting the position and direction of the application points. In industrial production, the term curtain application may also be used for systems in which the product is distributed from above or from multiple points and allowed to flow over the surface of the component. To avoid unnecessary terminology overlap, both applications can be considered part of the same family of methods based on coating flow.
The fundamental difference compared with spraying is therefore the transfer method: in spray painting the product is atomised, while in flow coating it flows directly over the part. The quantity distributed, viscosity, component orientation and the ability to drain and recover excess material are some of the parameters that must be assessed to achieve correct coverage.
Industrial powder coating
Powder coating is a different technology from methods based on liquid products. The coating is deposited in powder form, generally using electrostatic systems, and is subsequently subjected to a thermal stage that allows the film to form. The process is widely used to create protective and decorative finishes on metal components and is particularly suitable for production organised around dedicated coating lines.
Its inclusion among the main industrial painting techniques is therefore appropriate, but it is important to distinguish it from systems used to apply liquid coatings or functional coatings designed for metallurgical processes. Not all ATP technical products, for example, are powder formulations intended for electrostatic coating processes. The application method must always be verified in relation to the specific product.
Differences between the main industrial painting methods
The distinction between the different techniques becomes clearer when considering how the product reaches the component.
| Method | Application principle | When it can be useful |
|---|---|---|
| Brush | Manual distribution of the product | Localised areas, small batches, selective applications |
| Spray | Atomisation and deposition of the product onto the surface | Large surfaces, controlled and repeatable applications |
| Dipping | Complete immersion of the component in the product | Coverage of large surfaces and complex geometries |
| Flow coating / curtain application | Continuous flow of product over the surface without atomisation | Coverage using automated systems and recovery of excess product |
| Powder coating | Deposition of powder material followed by film formation | Protective and decorative finishes produced on dedicated lines |
Viscosity and application control
Whatever method is selected, industrial painters must control the process parameters in order to achieve an effective result. Among these, viscosity is particularly important for liquid formulations because it influences how the product is transferred and distributed over the surface. A coating that is too fluid can cause runs or insufficient thickness, while excessive viscosity can make uniform distribution more difficult or prevent the use of certain equipment. Other important parameters may include the temperature of the product and component, the number of passes, the time between layers, part orientation and drying conditions.
Failure to control these elements can contribute to coating defects. Some of the main coating application errors should therefore be considered when defining and controlling the application process.
Which application method should be used for ATP products?
ATP Europe products include families with very different characteristics and functions: protective coatings, Stop-Off coatings, hot-working lubricants, boron nitride coatings and marking paints. It is therefore not correct to automatically associate the same application method with every formulation. Brush application, spraying, dipping or flow application can be used when compatible with the characteristics of the specific product and the process conditions.
The method is selected by considering both the formulation and the required result. A coating designed for localised protection of a specific area may require a different application method from a product intended to cover an entire component. To explore the different product families and first identify the most suitable technology for the application, see our overview of ATP paints, coatings and solutions for metals.
From coating selection to the application method
The choice of industrial painting method should take place after the material, the function required from the coating and the process conditions have been clearly defined. In other words, the first step is to determine what the coating needs to do and which formulation is compatible with the operation; the next is to establish how to apply it in a uniform, controlled and repeatable way.