Powder coating is a dry coating process involving specialist coating materials. These materials combine polymer resins, pigments, curatives and other curing agents.
There are two broad categories of powder coatings:
Thermoplastic powder coatings come from synthetic materials and include polyvinyl chloride (PVC), polyolefin and polyester. They offer excellent levels of protection from physical damage and wear and tear.
Thermoset powder coatings are based on a chemical reaction between their ingredients, known as cross-linking. This alters their physical properties. Generally, they offer a harder finish than thermoplastic coatings, with better heat resistance. They include epoxy, epoxy-polyester hybrids, acrylic and silicon.
You apply powder coating as a dry material, using a spray gun.
Powder coating is a form of paint with no liquid carrier. Instead, you apply it using an electrostatically charged spray gun.
The gun gives the powder a positive charge when it emits from the nozzle. The surface you apply it to is negatively charged.
By positively charging the powder, you ensure that it sticks to the substrate, despite the pull of gravity and the aerodynamics of the spray.
This form of dry coating ensures an even finish, even where there are hard-to-reach recesses, sharp edges or angles.
The powder coating process is in three stages:
Preparation is critical to applying a powder coating successfully. This involves degreasing the surface you wish to coat and washing it thoroughly. Some surfaces may also require other pre-treatment options, chromating and phosphating.
After preparing the surface, you apply the dry powder coating using a spray gun (see above).
The final part of the process is curing. This involves baking the coated surface in an oven.
The curing stage of the powder coating process is where you bake the coated surface in an oven.
Applying heat inside a convection oven should ensure that each component in the powder coating reaches its optimum temperature.
Once this happens, the dry powder’s resins melt and fuse together. This creates an even finish.
Following the right curing schedule for a specific type of powder coating is essential to get the best results. This schedule is based on the part metal temperature (PMT) of the specific item you are coating.
The minimum curing temperature is 160°C, but some thermoset powder coatings will cure rapidly at higher temperatures. Some in as little as 10 to 15 minutes.
Once the curing is complete, the coating needs to dry.
As an alternative to liquid paint, powder coating is extremely versatile and is easy to apply.
Due to its application method, it provides a uniform coating to products and parts, even where they have sharp edges or narrow recesses.
The application process is rapid and minimises waste. Also, any over-sprayed powder is reusable.
With paints, you can struggle to get a satisfactory finish with just a single coat. But with dry powder coating, you can achieve this straight away.
With a broad range of coatings available for different applications and with RAL colour matching, powder coatings can out-perform liquid paint and offer plenty of options depending on the end application.
Powder coatings are more environmentally friendly than liquid paints (see below).
Liquid paint contains solvents that are volatile organic compounds (VOCs). These include various chemicals emitted as gases.
Solvents help to dissolve or disperse various components in paints, such as resins and pigments. But the chemicals in solvents are environmentally hazardous.
These environmentally hazardous solvents include acetone, naphtha, toluene and turpentine.
Consequently, liquid paint poses environmental and safety-related challenges for both its transportation and disposal.
This is not the case with powder coatings. They contain no VOCs or other harmful by-products.
They are easier to transport, store and dispose of and can mean fewer costs that come with putting workplace ventilation systems in place.
Providing you apply it properly, powder coating can last decades. Many coatings come with guarantees of 25 years or more.
Various types of powder coating will carry different warranties, that reflect their end-use.
For example, where a coating is for prolonged outdoor use, including exposure to direct sunlight, its warranty should reflect this.
You should look for the right kind of powder coating for your specific application.
As well as providing robust protection for parts and surfaces, powder coating makes them look good too.
Rather than choosing to patch up scratched metal surfaces with paint, applying a powder coating over the whole part will give it an even finish.
As an alternative to liquid paint, powder coating is fast and effective and can offer years of protection.
It’s the perfect way to revive scratched surfaces and leave them looking as good as new.
Powder coating can help metal resist corrosion.
As a tough, durable finish, powder coating protects metal surfaces, parts and products from the effects of corrosion.
It is resistant to cracking, chipping, peeling and abrasion and offers protection from UV ray damage, water and severe weather.
It adheres well to metal, giving it a protective outer shell and providing an even coverage to sharp edges and corners as well as flat surfaces.
While powder coating cannot protect surfaces that already have rust, it will prevent rust from building up if it is properly applied and maintained.
You can apply powder coating to a wide variety of surfaces and parts, including:
For more details about powder coating and its many applications, please contact us.