First developed in the 1960s, powder coating has become an increasingly popular alternative to liquid paint, and now makes up more than 15% of the industrial finishing market.
Versatile in its applications and both long-lasting and durable, powder coating is an ideal metal finishing method well-suited to a diverse range of projects and industries.
But what is powder coating, and what makes it so desirable?
Powder coating is a process of finishing that offers an attractive alternative to typical paints. The end result is similar, but with added advantages such as greater resistance to harsh weather and outdoor exposure, quicker application, and variable texture finishes.
Powder coating is a dry medium, which means it does not need time to dry out and is safer to apply in enclosed spaces. With no volatile organic compounds, it’s kinder to the environment and for human health while lasting longer than a regular coat of paint.
The powder coating process is generally broken down into three stages:
• Preparation and pre-treatment
• Application of the powder coating
• Curing of the powder coating under heat
The coating is usually applied as a free-flowing dried powder using a spray gun, and typically onto metals. This particular method applies an electrostatic charge to the powder which causes the particles to be attracted to the substrate prepared in the pre-treatment process. Once the powder has been applied, the coated parts are then cured using high heat, wherein the temperature causes a chemical reaction that hardens the resins and sets the powder. In addition to metal substrates, powder coatings can also be used on a range of non-metallic surfaces such as plastic.
Powder coatings can be thought of as similar to paint, minus solvents. They are made up of a polymer resin such as epoxy or polyester, combined with curatives, levelling agents, pigments, and other additives. These ingredients are melt mixed, cooled, and then ground into a homogenous powder.
Different types of powder present different strengths and weaknesses. Epoxy powders, for instance, tend to ‘chalk’ in the sun and their colour fades. Weather degrades them quicker, but for indoors use, they’re ideal.
From items you use every day to heavy-duty industrial machinery, powder coatings are used to provide an attractive and durable finish for all kinds of products across a range of industries. There are several benefits to this finishing process that make it superior to traditional liquid paint in many applications.
From a functional standpoint, powder coatings offer a greater level of durability. Powder-coated surfaces provide significant resistance to everyday wear and tear, unlike liquid paints which are delivered using an evaporating solvent. Powder coatings can be applied in thicker coats without sagging, dripping, or running. For industries like construction, automotive, electrical engineering, and agriculture, this reduces the need to replace equipment as powder coating can last for decades, ultimately saving businesses money over time.
In addition to its durability, powder coatings are more eco-friendly than traditional paint finishes. Because this method does not require the use of solvents, they result in a reduced carbon footprint. This reduces the burden on companies to dispose of volatile organic compounds, and remains compliant with industry regulations. The process of powder coating also cuts down on the amount of waste materials and material can often be recycled.
As with many jobs that require precise knowledge and expertise, costs can varying depending on the work involved and the scale of the job in question.
Simpler powder coating jobs, such as small automotive parts and landscaping features, may be charged at flat rates as opposed to charging by the measurement. Additionally, non-new substrates could require pre-treatment in the form of cleaning and removing grime, rust, or oil to get them ready for a powder coating. Extra preparation such as this is likely to add to the cost of a job.
Powder coating jobs can cost less than a tin of paint at around £15 per square metre, or can cost in the order of hundreds depending on the scale of your job. Like with all important jobs, it’s best to get a quote and discuss to understand the best price for the best work.
Powder coating lasts for a long time. Typical lifespan of a well-done coating is 15 to 20 years, though various factors might reduce this over time. Powder coating is tough and resistant, but UV and weather exposure, prolonged abrasion, and other factors can wear it down given enough time.
The staying power of a coating depends on the type of material used and the applications of the item that has been coated. Epoxy coatings, for instance, have a tendency to deteriorate when exposed to UV. Powders like fluoropolymers should last longer for outdoor applications in the face of weather and sun exposure.
Thermoset powders form chemical bonds when cured, making them highly durable and ensuring that they cannot be melted away. This makes them impossible to recycle, contrasted with thermoplastic powders, but they are the better choice for fully futureproof work.
Tomburn’s aluminium coatings come with a 30-year guarantee, ensuring peace of mind for each application.
Most powder coating jobs can be completed in a single day, though this will always vary. Pre-treatment can take longer for different substrates and the size of the surface area to be covered will dictate the time investment needed.
Despite this, powder coating is generally fast and efficient. Unlike paint, it doesn’t need time to dry without contact to dry out. It also disperses evenly and with greater ease than liquid paint, clinging as electrostatically charged particles rather than needing to be applied and spread in an even coat.
Once the substrate has been sprayed, the coating must be cured. This requires heat to harden the resins in the powders. Since powder coatings can withstand high heat, curing can typically be done in as little as 30 minutes.
Using a dry medium like powder coating means the work can be done faster and enjoyed faster, without needing to wait long stretches between coats.
There are a variety of colours and finishes possible with powder coating.
Colour options for powder coating number in hundreds to thousands, depending on options offered by providers. These include NCS shades and Pantone, which provide standardised colours to choose from. Coloured powders can also be custom made for a fee by certain providers.
Powder coating can also be finished with a range of textures, typically referred to as special effects. These can include:
The fine roughness of this finish diffuses light and gives it a matte appearance with low gloss. The rough surface also aids with grip, making it appealing for handles and other areas that need to be gripped by hand. Sandy textures offer great scratch resistance and can even help hide small surface imperfections.
Wrinkle texture coatings have greater roughness than sandy finishes but still offer many of the same advantages. They’re tough, good for hiding surface imperfections, and lend a subtle, sophisticated look to a piece while still providing good grip and being pleasing to the hand and eye.
Hammer finishes, sometimes known as hammertone, also have an uneven surface texture but with a smooth, semi-glossy factor. The end result is a pockmarked surface with lots of small smooth depressions. It’s highly popular with garden furniture and décor pieces, and many praise it for looking imperfect whilst still providing a nice cover to the substrate.
Gloss finishes are the most akin to traditional paint coatings, being smooth and level with very little friction. Gloss finishes are ideal for surfaces that need to be cleaned frequently. Powder coating with a gloss finish is easier to ensure than with liquid paint, making it a particularly attractive method of finishing in this regard.
Other specialist finishes are possible with powder coating. If you have a specific need or aesthetic in mind, ask your specialist when making an enquiry about your job.
There are some contexts wherein powder coating won’t be suitable or even possible to use. Powder coating on wood has seen some advancement, but there are still technological limitations that might not make it practical in many ways.
For substrates that can’t be grounded to attract the charged powder particles or can’t be safely heated to allow the powder to set, liquid paint will still serve as the best finish. For the vast majority of metal parts, powder coating will be better than using liquid paint for a number of reasons.
First, it doesn’t contain any volatile organic compounds (VOCs), which are solvents that get released into the air as paint dries. VOCs are hazardous to health and have seen reduced usage in paints over recent years for this reason. VOCs are intended to evaporate once paint is applied.
Powder coats, however, are dry mediums and as such don’t off-gas in the same way as liquid paints. This makes them safer to use and don’t need to be avoided for as long as paint, which takes time to dry fully and gives off strong chemical odours as it does so.
This also makes powders safer to use in contexts where they will come into contact with soil and organic matter, as they will not chip and flake where chemicals will be released into the environment. Park benches, landscaping features, and garden furniture are all ideal to powder coat rather than paint.
Since powder coats don’t need to dry, they are also ideal for use in public spaces or areas there the substrate will require regular contact. Where a coat of liquid paint needs to be protected while it dries – from weather and dust, while hoping that no people or animals accidentally ruin it – a powder coating is ready as soon as it’s been set.
Additionally, powder coating can be done quicker and in higher volume than liquid paint, with no risk of running, bubbling, or trapping dirt and hair. Due to the necessary preparation for applying powder coats, substrates are often clean and ready as a matter of process.
At Tomburn, we have over four decades of experience in powder coating. We know just how to give your item the perfect finish to the highest possible standards. Our innovation and commitment to being the best in our industry is what has maintained our reputation for excellence in powder coating for so long.
We can answer and all queries concerning the clean, convenient method of powder coating.
For further information, contact us today on 02392 692 020.