Covering a substrate with a substance; coating meaning
Coatings are substances which are applied on objects and surfaces to change the substrate’s properties or appearance as well as to protect it from wearing out. There are many different types of coatings and coating applications due to the fact that they are suitable for different substrates and have different properties.
Some for example are ideal for wood whereas others are more suitable for metal surfaces. When it comes to properties, the use of coating is important; floors need durable coatings such as epoxy or PU systems, and stair coatings should have anti slip properties. The basic manufacturing coating process is similar in most types of liquid paints. The main ingredients are solvent or water, fillers, pigments, binder and additives.
Coating applications and process
There many different coating applications and methods depending on the type of product and surface. For example most poly urethane and epoxy coatings consist of two components, which means that the application includes mixing the components. Therefore, a one pot system applications can be simpler. The coating process for industrial and decorative coatings are very different from each other. Most home decorators apply paints and coatings with either roller or brush.
Also spray solutions are available. Other application methods such as powder coating are possible to realise at home, however, they do require professional equipment and more knowledge on the coating process.
Industrial applications, for their part, are often more complicated and they must be time efficient. Therefore, depending on the product, industrial coating applications are often automated. The coating process in general can be carried out by dipping, brushing, pouring, spraying, with a roller or an automated process such as coil coating.
Every coating process includes cleaning the surface, applying the product and curing. In general, the surface should be dust/dirt and grease free. The further preparation of the surface may include sanding and applying a sealer or primer, depending on the recommendations. After applying the first layer, bringing on mid or topcoat follows. Sometimes reaching the ideal result requires more than one layer of coating.
Once the coating layer is ready, finishing the job thus, curing the coating takes place. Curing refers to letting the coating harden and dry. This can be done with several methods such as UV curing, high temperature curing (oven for powder coatings) or naturally by giving the surface time to dry. Also the curing process is dependent on the type of paint.Choosing the right coating
A number of factors affect the suitable coatings and the best deposition method. To begin with, the substrate material plays an important role in choosing the right coating meaning that the product must be suitable for the substrate; usually for example wood and meta require different coating products. Furthermore, the geometry of the substrate matters; for not every coating flows well onto complex shapes.
Naturally, also the function of the coating is important; it might for example, have to resist chemicals or abrasion and be able to emit light. The function also has a link to the ideal thickness of the layer. Last but not least, the product should always be durable and cost-efficient.
Primer and undercoat
Use a primer if you are coating or painting a new and uncoated surface. If you paint an existing surface that has been coated or painted before, use an undercoat.
More than a protective layer
Coatings are much more than merely a protective layer; the world of coatings became even more versatile after the introduction of nanotechnology and its applications in coatings. Nowadays, nanotechnology allows development of for example water- repelling- and self-cleaning coatings.
Innovative smart coatings
Nanotechnology is used also in developing so-called smart coatings which consist of programmable materials which have physical, chemical, mechanical and electrical properties. These materials may be responsive to for example changes in light, temperature or pressure.
Smart coatings include:
- Self-healing coatings
- Colour changing paints
- Glow in the dark systems
- Antibacterial solutions