Knowing which type of finishing application works best for each scenario becomes of great importance to the ultimate success of a project. As a result, anyone considering making use of one of these finishing techniques must know the basic principles of the technique, the process, the advantages, and the drawbacks.
The Importance of a Finish in Sheet Metal Fabrication
Metals like carbon steel and ductile iron contain iron. This metal reacts with oxygen to form rust if left unprotected. For this reason, surface finishing becomes essential. Many people assume colorful exteriors on these metals only serve a decorative purpose, but that is not the case. They function as a barrier to prevent corrosion. Men and women find they have a choice to make with the finish. Powder coating and wet paint stand as the two options offered today.
While both finishes contain additives, pigments, and resins, only wet paint comes with solvent. Powder coating lacks this element. This single element distinguishes the two finishes, and they each come with benefits and drawbacks.
The solvent found in wet paint works to keep all components in suspended liquid form. Powder coating, in contrast, comes as a dry powder. This difference in chemical composition dictates how the technician applies the finish, matches colors and textures, and the training the operator undergoes. What must a person know about these options before making their decision?
What is Powder Coating?
Powder coating involves the application of an electrostatic coating to a surface. The coating comes as a free-floating dry powder and requires heat to finish the coating process. Technicians apply the powder using an electrostatic gun that provides the powder with a negative charge. The grounded part attracts the negatively charged powder to allow for a fast-even application.
Manufacturers make this product using a variety of things, such as straight epoxy, acrylics, polyurethane, or polyester. With the use of powder coating, individuals find they get a product with a hard finish that offers more durability than conventional paint. Companies use powder coating for everything from auto parts to appliances found in the household.
The Process Used with Powder Coating
Companies use one of two processes with powder coating, When they use additional chemicals that react to the powder when heated, they refer to this as thermosets. In contrast, thermoplastics require no additional chemicals. Instead, they melt and flow into the coating. Regardless of which process they use, the finished products look similar.
With either process, the manufacturer creates the plastic by taking the powder input and binding the components. They then heat this mixture and roll it out. The next step involves breaking it into chips before they grind it into a fine powder. However, the user must take certain steps before applying the powder to the metal.
First, they must clean it to remove any oil and debris, as their presence interferes with the ability of the dry power to adhere to the surface. The technician then applies the dry powder electrostatically. This involves charging the powder particles and the object being coated with a high electrostatic surge. The surge enhances the process by increasing the efficiency and productivity by roughly 95 percent. This leads to less waste and a more thorough coating of the object.
The sprayed powder coating must cure for ten minutes at temperatures of up to 400 degrees. This allows the finish to set onto the object while enabling the powder to melt and flow around the object. As the heat metals the powder, it binds the polymer to make a stronger material with a tight network-like finish. The curing coats the sheet metal while binding the polymer to produce a tight, heavy finish.
Why Choose Powder Coating?
Users find they get many benefits when they select powder coating. The thick finish produced by this process serves as a durable and long-lasting alternative to conventional paint. Objects require only one coat to get these benefits, so the process is quick and easy. In addition, individuals who desired a textured finish find powder coating serves as the right solution for their needs. The thin powder coat comes with a natural texture, one the technician can enhance in a variety of ways.
Experienced users know how to manipulate the powders to achieve custom finishing colors and textures. The process creates an even finish that cannot be obtained when they use other methods. The technician sprays and heats the powder with no drips or traces of application.
Powder coating resists scratches, chips, and other wear better than wet paint and plating because of the thermal bonding that occurs during the curing process. Furthermore, it keeps color better over time. The powder coatings come with a polyester base that allow them to withstand the elements better than paint.
One benefit of powder coating involves the ease of storage. Not only is powder coating easier to apply, users find it is safer to store. Using this material protects the health and safety of all who come into contact with it. The powder doesn’t contain fluids, so it doesn’t emit volatile organic compounds which are hazardous to human health and the planet. However, the process comes with drawbacks a person must know.
The Drawbacks of Powder Coating
Powder coating produces a thick finish. Attempting to thin the polymer results in a bumpy texture, such as that one might see on an orange. In addition, small projects rarely benefit from powder coating because of the cost of the materials, oven, and electrostatic booth needed to carry out this work.
Men and women find it takes more effort to achieve a custom powder coat color than it does with wet paint. In fact, custom colors call for a special production run. The color of the coatings comes from the plastic ground to form the coating, As the powder coating contains no solvent, mixing two colors results in a speckled pattern rather than a blending of the two shades. The cost of a custom color for a small project often outweighs the benefits of using that color.
What is Wet Paint and Plating?
A traditional method of coating sheet metal, wet paint involves applying liquid paint to a surface to finish it. Most processes involved with sheet metal fabrication use a pump, a spray, or a pressurized device to apply this paint to the surface evenly. Plating, as seen with jewelry, involves depositing metal on a conductive surface, and manufacturers use this process to inhibit corrosion, harden a substance, improve paint adhesion, for decorative purposes, and more.
What Does the Wet Paint and Plating Process Involve?
Before the technician applies liquid paint to a surface, the surface must first undergo a thorough cleaning to remove any dirt and debris. The technician then wet-blasts liquid paint to an even thickness. For most surfaces, a thickness of 15 to 20 micrometers remains the best option. The technician continues to apply the paint until they achieve the desired thickness. Plating, on the other hand, remains more complex, and the technician must know what plating metal will be used and what effect the customer desires. In many cases, the technician covers the item with the desired metal and uses heat and pressure to fuse them. However, liquids, vacuums, and vapors serve as suitable substitutes for the heat or pressure used in this process.
The Benefits of Wet Paint and Plating
Certain items cannot stand the heat required for powder coating, and wet paint and plating allow for finishing of these items. Individuals find their color options expand when they choose wet paint, which is of importance in custom color work. The finish obtained with wet paint and plating remains much thinner than that seen with powder coating, and this process costs less, especially for smaller jobs. Finally, individuals desiring a high-gloss finish find it easier to achieve this goal when they use wet paint rather than powder coating. Nevertheless, wet paint and plating come with drawbacks.
The Drawbacks of Wet Paint and Plating
Durability remains an issue with wet paint. This process simply doesn’t compare to powder coating in this area. Additionally, wet paint comes with maintenance and refinishing requirements not seen with powder coating. Technicians must often apply multiple coats to get the desired results, increasing the risk of one or more flaws.
Wet paint serves as a flammable substance. When stored improperly, the paint could cause a chemical fire that is dangerous. In addition, research has shown this substance to be a health hazard to users, as it emits volatile organic compounds. Long-term exposure to these compounds leads to respiratory irritation and health problems. The risk increases when a person uses the wet paint in enclosed spaces. Furthermore, the volatile organic compounds serve as a significant source of industrial pollution.
Individuals need to consider both powder coating and wet paint and plating when they need an object finished. Work with Precision Finishing to determine which is best for the object being finished. The goal is to get a finish that is functional and appealing, and our team will help you determine how best to achieve this goal.
