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Learn the facts behind powder coatings

Update:02-06-2022
Summary:

You probably already know something called powder coate […]

You probably already know something called powder coated steel. But what makes it powder coated? Any free-flowing dry powder can be powder coated. The difference between it and standard liquid paint is that it does not require a solvent to help keep the binder and filler parts in suspension. The covering is electrostatically added and cured under heat to form a protective layer. Powders are usually made with thermoplastic or a type of thermoset and produce a durable finish that is stronger than regular paint. Metals such as white ceramics, aluminium extrusions and bicycle parts are powder-coated materials. This coating can be in the form of a common material used for toilet partitions.

Everything is good, right? Well, using powder coatings has some advantages over other types of coatings. Thicker coatings can be produced that do not have flow or sag characteristics. They emit very few volatile organic and natural compounds. Over spray can be reused, allowing every bit of the coating to be used. Manufacturing powder coatings has a smaller amount of hazardous waste. The product and cost are generally lower than some other liquid paints. In many cases there is no visual difference between vertically or horizontally coated surfaces. There are tons of effects that can be done that you wouldn't otherwise be able to do with other overlay types.

There are a number of disadvantages to using powder coatings instead of other types of coatings. While the coating process is simple for thick coatings, thin coatings are often difficult. If the coating is thinner, it has more exfoliated texture due to particle size and glass transition temperature. When it must be done, the purchase price will be higher than other forms of painting. While it can have the major advantage of reusing overspray, it will limit everything you can recycle if using multiple colors within your booth.

The most common properties of powder coatings are alloys between 30 and 50 microns in size and a glass transition temperature close to 392 degrees Fahrenheit. The texture of the surface depends on the commodity being produced. Many times, it's better to have a bit of a peeling look, which hides pretty much any imperfection inside the metal, which makes fingerprints less likely to show up. Sometimes, the coating is expected to be below 30 microns, and even the transition temperature is below 104 degrees, so it is thinner. The standard process used to achieve this thinner film is called the powder slurry method, which disperses approximately 1-5 microns of powder directly into water, resulting in a clean, thin coating.

There are generally two main forms of powder coatings, thermosets and thermoplastics. Along with thermosetting, the powder is baked and interacts with some other chemical groups within the powder to enable polymerization, which generally improves performance characteristics. Thermoplastics are different in that no other reaction takes place during the bake process, it just flows out to complete the coating. The main polymers used are polyester, polyester-epoxy, polyurethane, acrylic and pure epoxy.

Tunnel type powder curing oven for powder coating production line

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