Surface Preparation and Powder Coating at RA Construction
From this article, you will learn how we prepare surfaces for powder coating, what equipment we use, and what standards we adhere to in order to ensure the highest quality of surface, backed by certificates. You will also learn what polymerization is and why time and temperature are its most important parameters.
Reading the article will take you 5-7 minutes.
What does sandblasting of steel elements involve?
Sandblasting is a process of mechanically cleaning surfaces with a special device – a sandblaster, and an efficient compressor. Abrasive material such as sand or corundum is used for this purpose. It is an invasive and effective method for removing rust and other surface contaminants from profiles and thick sheets.
The first stage of sandblasting involves placing the steel elements in a special chamber. There they are subjected to a stream of abrasive grains under high pressure.
After the sandblasting process, the elements are ready for painting. It’s also worth mentioning that sandblasting removes contaminants and increases paint adhesion to the material.
What does powder coating involve?
Powder coating is one of the most modern and effective painting techniques, which involves covering the surface with powder paint, then curing it on the surface through a heat treatment process in an oven. This is a very effective painting method that ensures a durable, weather-resistant coating with high aesthetics.
Polymerization in powder coating
Polymerization in powder coating is a key element that allows for the creation of a durable and resistant coating on the painted element. During polymerization, powder paint particles melt and join together, creating a durable coating on the surface. On a chemical level, small particles (monomers) join together to form long chains (polymers). This process, of course, occurs under the influence of heat.
Temperature and curing time are the two most important parameters that affect the quality of polymerization. Too low a temperature or time can negatively impact the quality of the coating. On the other hand, too high a temperature or extended curing time can also result in damage to the paint coating.
What does the powder coating process look like?
The powder coating process begins with preparing the surface for painting. To achieve this, metal elements are subjected to sandblasting to ensure good paint adhesion to the surface and to remove any surface contaminants that could negatively affect the quality of the paint coating.
The next step is pre-heating in an oven, which enhances paint adhesion and affects the final quality of the surface. Then, the metal elements are electrostatically covered with powder paint and are again heated in a paint oven.
Powder coating technology - How is powder paint applied?
The paint is applied using a special spray gun, which charges the paint with electrostatic charges. The material to be painted carries the opposite charge, which attracts the paint to the metal surface and ensures uniform coverage. This technology allows for efficient coating of painted elements.
What is powder paint made of?
Powder paint is a special type of paint. It consists of powder particles of pigments and organic resins. The pigments used in powder paints are made from various mineral substances, such as oxides, hydroxides, or organic dyes, and the organic resins are usually thermosetting polyesters or epoxies.
Powder paints are characterized by high durability and resistance to mechanical damage, corrosion, and atmospheric factors. They are also more environmentally friendly than traditional paints, as they do not contain organic solvents or heavy metals.
Powder painting performed under appropriate conditions is eco-friendly.
Dimensions of the paint oven
After applying the powder paint, the steel elements are transported to an oven measuring 7 x 2 x 2.5 meters. They are then baked. After this, they are removed from the oven in order to apply the paint and then returned. During the curing process, the powder paint melts and hardens, forming a durable coating highly resistant to mechanical damage, corrosion, and atmospheric factors.
In what colors do we powder coat?
At RA Construction, we offer powder coating in virtually any color from the RAL palette. Standard colors (available immediately) are RAL 7016 and RAL 7001. Other colors are available on order.
What is the RAL color palette?
The RAL color palette is a European color standardization system. The RAL system (Reichs-Ausschuß für Lieferbedingungen und Gütesicherung) was introduced in Germany in 1927 and has been continually updated and developed since then.
The main advantage of the RAL system is its universality. Because it is known and used worldwide, it allows for the precise identification and replication of colors.
Advantages of powder coating
Durability – Powder coating creates a coating that is more resistant to scratches, corrosion, mechanical damage, and the effects of weather conditions than traditional spray painting;
Efficiency – The painting process, combined with trained staff, allows for the application of a single, evenly covering layer, which eliminates the need for multiple layers;
Environmental protection – Powder coating, when conducted under appropriate conditions, is more environmentally friendly than traditional spray painting. It does not require the use of solvents and emits significantly fewer pollutants;
Wide range of colors and finishes – Powder coating offers a wide range of colors and finishes, including matte, gloss, metallic, and texture.
Powder coating price per square meter
The cost of powder coating depends on several factors such as the size and shape of the object, quantity of items, type of powder paint, quality and type of surface, and the complexity of the coating process. Additionally, whether we apply just the color or both color and primer.
At RA Construction, we strive to tailor our services to the individual needs and requirements of our clients. Each inquiry is assessed and priced on an individual basis. However, powder coating prices typically start from around 50 PLN per square meter.
It is important to note that the mentioned cost is for the powder coating itself. Surface preparation, such as sandblasting, would be an additional cost. Therefore, it is best to contact us and provide detailed information about your project, so that we can prepare a quote that is specific to your needs.
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Standards governing surface preparation and powder coating processes
In order to ensure the highest quality of services provided, powder coating requires knowledge and adherence to several standards that define requirements for surface preparation, coating quality, and more. Below are a few examples
PN-EN ISO 12944
This standard specifies the requirements for corrosion protection for steel elements, including paint coatings. Within this standard, there are five categories of corrosion environments defined, which impact the selection and type of paint and application technology. These categories include dry, humid, marine, industrial, and special environments, such as chemical atmospheres. The categorization helps in determining the appropriate paint system and coating technology to ensure effective corrosion protection in specific environmental conditions.
PN-EN ISO 8501
This standard, in turn, specifies the requirements for surface preparation prior to painting. In the case of powder coating, surface preparation is one of the crucial stages of the process that determines surface quality. The mentioned standard provides detailed guidelines for various surface preparation methods, such as sandblasting, shot blasting, chemical cleaning, and mechanical cleaning. These guidelines ensure proper surface preparation and contribute to achieving the desired adhesion and durability of the powder coating.
PN-EN ISO 2409
The standard that specifies the requirements for assessing the adhesion of paint coatings to substrates is known as the „Adhesion Testing of Paint Coatings” standard. This standard covers various paint coatings, including those used in the powder coating process. It describes the methods for conducting adhesion tests of paint coatings to substrates. These tests evaluate the bond strength between the paint coating and the substrate, ensuring that the coating adheres properly and withstands mechanical stresses.
ASTM D3451
The standard that specifies the requirements for testing the quality of paint coatings, including powder coatings, is ASTM D3451. This standard describes methods for testing the corrosion resistance of paint coatings. The testing involves applying the paint coating to a sample and subjecting it to cyclic exposure tests with a salt solution. The test results allow for determining whether the paint coating is corrosion-resistant and meets the requirements of the standard. These tests are crucial in evaluating the long-term durability and performance of the paint coating under corrosive conditions.