Advantages and disadvantages of powder coating
When deciding to choose powder coatings, we always compare it with liquid paints. In this regard, we will consider the benefits and limitations of powder coatings. Liquid paint and powder coating have many differences both in production and application. Apart from quality, the pros and cons of powder coating are also related to the following.
Below, we have listed the benefits and limitations of powder coating compared to liquid paint.
Benefits of powder coating
No solvents, environmentally friendly
Powder coating contains no solvents and is 100% solid, this is why it is environmentally friendly. Powder helps reduce the health hazard to operators.
The odds of conflagration are very low
The fact that powder coating contains no solvents makes it much less prone to conflagration compared to liquid paint.
Capability for thicker finishes
Powder coating enjoys high viscosity and is 100% solid so it can be easily produced in much greater thicknesses compared to conventional liquid coatings without runs or drips.
Use of waste powder coating
The system and equipment in spraying of powder coating is designed in a way that the powder which does not adhere to the substrate will enter the spray cycle again and is recovered and reused. This minimizes wastage and prevents sewage residue.
Very good mechanical and physical properties
Powder coatings have better physical and mechanical properties and are much harder and more durable than conventional paint. This quality is one of the important factors in evaluating powder coatings and is very effective compared to liquid paint.
Variety of effects and finishes
Powder coatings can be applied in a wide range of colors and textures that are not readily achievable through conventional liquid coating methods. Some examples are: leather, hammer tone, sand texture, wood effect, metallic, and crocodile skin. Powder coatings can be formulated for both protective and decorative applications. The final finish achieved by the powder material ranges from matte to glossy. The variety in the aesthetics of powder coatings is essential in its evaluation and in choosing it over liquid paint. In fact, many industries have chosen only powder coatings because of this quality.
Limitations of powder coating
Production and application problems of powder coatings
Considering that the production process and blending of powder coatings is carried out in molten form, it is not possible to change the color after production. Whereas in liquid paint we can change the color in all the stages, even when applying the paint, by adding pigment paste.
Thin coatings are difficult to produce
Powder coatings are 100% solid and because of this, with a minimum amount of application the initial thickness is formed and it contains no volatile components. This makes it impossible to have thicknesses less than 25 microns. Whereas in liquid paint, we have paint thinner and it is possible to have a lower percentage of solids, film thickness can even be as low as 10 microns.
Not applicable on large surfaces such as ships
The spray equipment and method of application of powder coatings make coating only possible in spray chambers. Substrates must be charged and after having been coated, enter a curing oven heated up to 200 degrees. Considering these conditions, it is not possible to coat and cure large substrates.
The limitation in the mechanism of curing in an oven
Powder coatings only dry and cure in temperatures above 180 degrees. Whereas liquid paints are varied and could dry up even in room temperature.
Powder coatings can used for coating metals and non-metals
Considering the method of application and conditions of charging the substrate, as well as the fact that the substrate needs to be cured up to 180 degrees, it is not possible to coat non-metal substrates.
Powder coatings can be applied to non-metal substrates too. In fact they have been commercially applied, in high volume, to MDF (medium density fiberboard) for over 20 years. Some coaters use UV curable powder coatings, others use low temperature thermosets that can cure as low as 130 degrees.
Taking into consideration the benefits and limitations of powder coatings, and the selected product to be coated, you can evaluate whether coating metals with liquid paint or powder is more suitable for you. Taking into account the many benefits of powder coatings, most industries nowadays have replaced liquid paints with powder coatings. With increasing technologies in the powder coating industry, many more industries are turning to them.
Prepared by: Mojtaba Zeinal