Powder coating is a widely used application, protecting metals from corrosion and improving their aesthetic appeal. Can aluminum be powder coated? Is it necessary since aluminum is already corrosion resistant?
- Can Aluminum Be Powder Coated?
- Why Powder Coat Aluminum?
- Aluminum Powder Coating Process
- Surface Preparation
- Powder Application
- Coating Thickness on Aluminum
- Aluminum Powder Coating Colors
- Does Powder Coating Weaken Aluminum?
- Powder Coating Aluminum vs. Anodizing
- Aluminum Powder Coating vs. Paint
- Is It Better to Powder Coat or Paint Aluminum?
Can Aluminum Be Powder Coated?
Yes, aluminum can be powder coated. Some manufacturers warn that the powder coating process could harm the metal’s integrity, but this depends on the powder coating methods being used. When carried out correctly, powder coating will not harm aluminum, and the resultant finish will improve the part’s corrosion resistance, wear resistance, and aesthetic properties.
Why Powder Coat Aluminum?
Aluminum is a lightweight metal widely used in both aesthetic and functional applications. While aluminum is naturally corrosion-resistant, some applications call for additional corrosion protection, achieved through powder coating. This process could also improve the metal’s wear resistance, change the color and surface finish, and create a reflective surface.
Aluminum Powder Coating Process
The powder coating process consists of three main parts: pretreatment, powder application, and curing. In this section, we break down each step and analyze essential factors that should be considered.
During pretreatment, the part to be coated is cleaned in several stages to remove all dirt, grime, and impurities from the surface. This is an essential step since impurities could negatively affect the powder’s adhesion to the surface, ruining the outcome.
When encountering oxygen, a thin layer of aluminum oxide forms on the metal’s surface. For effective powder coating, this layer must be removed through power washing. This exposes the pure metal surface to be coated.
Aqueous Alkaline Cleaning
Next, the part would undergo aqueous alkaline cleaning. Here, the aluminum part is dipped in a solution containing between 2 and 5% sodium compounds. For effective cleaning, a soft-bristle brush is used to gently brush the surface, removing any impurities. This brush should have nylon bristles, not copper or steel since that could damage the surface.
Following this scrubbing, the part is rinsed using warm water or water under pressure. Next, it is dried thoroughly, preferably in a heated environment, ensuring that all excess water is removed from the surface.
Solvent cleaning follows, removing grease and oil from the part’s surface. Here, mineral spirits or similar cleaning chemicals are applied to the part using clean rags. Once properly wipes down, the part is rinsed again, using hot water or water under pressure, as before. The part is then dried in a heated environment, ensuring completely dry before commencing the next step.
If any obvious dirt remains on the part, it can be cleaned by hand or by using a power tool. Again, the part should be rinsed and thoroughly dried before carrying out the next step.
Here, any remaining aluminum oxide is removed from the metal’s surface, and the surface is roughened to improve powder adhesion. To this end, one of two methods is generally used: sweep blasting and phosphate treatment.
During sweep blasting, pressurized air is used to blast abrasive media at the metal’s surface. Aluminum or magnesium silicates are generally used, although various other abrasive media could be used.
During phosphate treatment, a phosphate solution is applied to the metal’s surface. This can be done through complete immersion, surface spraying, or soft bristle application. Aluminum reacts with this solution, converting the surface into crystalline phosphate coating, which improves powder coating adherence. The process requires between three and six minutes, after which the surface should be thoroughly rinsed with water and dried again. Powder coating should take place immediately after this to prevent any new dirt from attaching to the surface.
During powder coating, electrostatically charges powder particles are flung at the metal’s surface. The aluminum part to be coated is electrostatically grounded. This difference in charge creates attraction between the powder particles and the metal’s surface, allowing them to stick to the surface.
Once the desired coating thickness is achieved, curing takes place. Here, the part is heated to the desired curing temperature, usually between 350 and 400֯F (176 – 205֯C) for around 10 to 20 minutes. The curing temperature and duration depend on the powder used and the coating thickness.
Coating Thickness on Aluminum
Powder coating varies in thickness depending on the application. Smooth surface layers of between 2 and 4mm are typical. When applying powder coating layers thicker than this, you risk orange peel and pockmark effects. While this is generally not desired, some applications warrant this aesthetic sacrifice, given the extra coating thickness achieved.
Aluminum Powder Coating Colors
Powder coating is available in any color imaginable and in a variety of finishes. These include matt, gloss, satin, high-gloss, super matt, and textured. With the latest technological advances, color gradients are also available.
Does Powder Coating Weaken Aluminum?
While powder coating in itself doesn’t weaken aluminum, some pretreatment processes could. Sweep blasting, or sandblasting, could damage the metal’s surface, especially if the part in question is fragile. Some worry that the heat necessary for curing could damage the metal since aluminum anneals at far lower temperatures than stainless steel. This is unlikely, though, since aluminum anneals at 650֯F (343֯C), and powder coating curing generally requires a maximum of 400֯F (204֯C).
Powder Coating Aluminum vs. Anodizing
Anodizing is an electrochemical process used to improve aluminum’s corrosion resistance. To this end, it increases the aluminum oxide surface layer’s thickness. Anodized parts are easy to maintain through periodic cleaning with water and mild detergent.
Unlike other surface coatings, the anodized layer won’t peel or flake since it’s part of the metal and not just a coating. It is also impervious to sunlight and will thus not fade over time. However, the anodized layer is vulnerable to attack from acidic pollutants, common in urban areas.
Anodized coatings are translucent and are thus limited to matt or gloss finishes with no intended color variation. However, these finishes often vary in color between batches, causing unwanted color variation in architectural projects.
Powder coatings are available in various colors and finishes and are highly consistent between batches. Maintenance is simple – since powder coating is chemically resistant, it can be cleaned using industrial-grade chemicals. Dents and scuffs are also easily repaired using a liquid repair agent.
Both powder coating and anodizing call for correct application. When misapplied, both methods are likely to produce poor surface finishes, with typical streaking and orange peel effect.
Aluminum Powder Coating vs. Paint
Powder coating and painting are the most commonly used surface protection for aluminum. Both are available in a variety of colors and finishes, and both are easily applied. That is where the similarity ends, however.
Powder coating is far thicker than paint. This means that powder coating offers more protection against environmental factors than paint does. It also has greater surface adhesion than paint, making it less likely to chip or flake.
Paint is inflexible. When the metal it’s painted onto vibrates or moves, tiny cracks form in the paint’s surface. This leads to chipping and flaking. Conversely, powder coating is flexible, allowing it to move with the metal. This flexibility makes it far less likely to chip or flake.
Powder coating’s flexibility allows it to absorb surface impacts, such as scratches, nicks, and dents, making it far more hard-wearing than paint.
Some types of paint offer a measure of corrosion resistance, but powder coating is inherently corrosion resistant. Here, again, it offers greater protection than paint.
Is It Better to Powder Coat or Paint Aluminum?
Powder coating outperforms paint in all aspects of surface protection. Since it is more hard-wearing and less likely to chip or flake, it also calls for far less maintenance and reapplication than paint.
Is it possible to powder coat aluminium? ›
Powder Coating on Aluminum. Powder coating is a versatile, environmentally friendly finishing process suitable for interior or exterior applications. Powder coating aluminum products adds a durable layer of protection that you can customize to match your preferred thickness, texture and color.What is the process of powder coating aluminum? ›
Powder coating is the process of spraying electrostatically charged paint (in powder form) onto your extrusions. Unlike liquid paint, powder coating doesn't require a solvent. So it's VERY important that the surface of every extrusion is properly pre-treated.How good is powder coated aluminium? ›
Durability: Despite its lightness, powder-coated aluminum is tough. It can withstand rigorous outdoor use and last for years.How long does powder coating last on aluminum? ›
Powder coating finishes can last up to 20 years, but due to the consistent use, exposure to UV light, and outdoor environment may break it down faster.Which coating is best for aluminum? ›
Polyvinylidene Fluoride (PVDF) Resin
Since PVDF coatings also resist fading, corrosion, and chalking, they're good choices for aluminum components in highly noticeable areas, such as on building exteriors.
Chemical Pretreatment of Aluminum Prior to Powder Coating
Chemical pretreatment is necessary to promote powder coating adhesion by providing a proper substrate on the aluminum surface to passivate the aluminum surface by providing a conversion coating to receive the powder coating material.
Even though powder coatings commonly exhibit a natural wavy appearance that suggests they may be thick, the typical powder coat layer is less than 1/10th of a millimetre thin (< 100 µm).What are the steps to powder coating? ›
The powder coating process involves three basic steps: part preparation or the pre-treatment, the powder application, and curing.Is it better to powder coat or paint aluminum? ›
Aluminium powder coating is usually the desired solution, as it offers a number of advantages over wet paints. For example the powder coating ensures that a strong layer is formed over the aluminium.Do you need to sand aluminum before powder coating? ›
Simply put, yes. As touched on above, without sandblasting any type of coating won't properly adhere to the surface of a material. The sandblasting not only removes dirt and grime but leaves behind minuscule scratches that make it easier for coatings to sink into and bond with.
What is better than powder coating? ›
STEEL-IT® stainless steel based industrial coating – a top alternative to powder coating – is tougher, lasts longer, and offers superior protection against corrosion and abrasion.How do you prepare aluminum for powder coating? ›
Blasting the aluminum surface will remove the initial oxide layer and contamination and promote good initial adhesion. It also does enhance corrosion protection, but if the powder layer is too thin, moisture will break through and cause failure.What metals Cannot be powder coated? ›
Metals that are not electrically conductive, like those that use certain fillers, cannot be powder coated.Can you powder coat aluminum twice? ›
The Short Answer
Put simply, the answer – most of the time – is yes. There's nothing about powder coating that makes the material fundamentally incompatible with more powder coating. You can still have the powder applied and cured to form a new coating that looks just like new, in most cases.
The anodized coating is an integral, hard substance that protects the base metal and makes it resistant to chipping, peeling, or flaking.
Aluminum oxide is a hard, durable, weather resistant coating that protects the base metal. The coating may be clear or colored using various methods. The coating itself grows from the base aluminum metal by way of the electrochemical process, so the coating is integral to the metal and cannot peel or flake.Will powder coating affect the strength of aluminum? ›
Because powder coating enhances strength and durability, your aluminum products will also be safer from dents and bends.What primer to use on powder coated aluminium? ›
For these jobs, an epoxy zinc-free power primer such as TIGER Dryprotector 69/70000 would be best suited for aluminum substrates. Designed to deliver superior corrosion protection for aluminum substrates and offers: Excellent corrosion resistance. Chemical resistance.Does aluminium need a special primer? ›
A self-etching primer is crucial in painting aluminum. Its formulation contains chemicals that etch into the surface of aluminum for the best bond. To apply the primer, spray it in thin coats according to the manufacturer's recommendations.What happens if powder coat is too thick? ›
Poor Powder Thickness or Coverage. Film thickness and coverage truly affects the overall finish of a coating. Too thick, and you will run into issues like orange peel or sagging; too thin, and you will be able to see the substrate – and any blemishes on it – easily through the film.
What do I need to prep before powder coating? ›
The first step to prepare a surface for powder coating is to wash away surface soils. Clean, reverse osmosis or deionized water should be used to remove dirt, dust, grime, and grease from the substrate. For tougher soils, you can use a pressure cleaner to remove them mechanically.How hot do you need to get for powder coating? ›
Unlike conventional liquid paints, which require an evaporating solvent for application, powder coating uses electrostatic application methods before being cured under high heat. Most powders require baking at around 350-400 degrees Fahrenheit for 10-20 minutes to fully cure.Do you need to clear coat after powder coating? ›
Common Applications for Clear Powder Coats
For metallic silver or chrome powder coats, we recommend adding a clear coat to protect your finish. The clear coat prevents moisture exposure so that the metal flakes don't oxidize over time or lose their shine.
If you want to try DIY powder coating at home, it will be even more challenging to carry it out correctly and safely. There are many challenges and risks you have to deal with when you attempt to carry out this process without the right expertise, equipment, and supplies.What kind of paint do you use on powder coated aluminum? ›
If your customer repaints, recommend using thermosetting acrylic, epoxy, polyester or polyurethane enamels. Although they may not provide the same quality, air drying enamels including aerosol spray can paints will adhere as well.Which is cheaper anodizing or powder coating? ›
Budget-friendly: Compared to anodizing or wet-coat painting, powder coating is a lower-cost, higher-quality finish. Durable: Powder coating has been proven to be one of the longest-lasting, most color durable, and strongest finishes available.Which is better anodizing or powder coating? ›
A. Anodizing is an inorganic finish, while powder coating is an organic finish. Powder coatings are some of the best organic finishes (paints) on the market. However, they cannot withstand the same abuse as inorganic finishes, such as plating or anodizing.Does powder coating chip easily? ›
Sometimes powder coating will chip or crack, and continue peeling just like an egg shell. Not only does chipped powder coating look bad, it can it allows the elements to wear away the precious parts you tried so hard to protect.What is the most durable type of powder coating? ›
Epoxies were the first widely used powders. They are very durable, offer excellent hardness and have arguably the best chemical and corrosion resistance of all available powders. Another plus of this type of powder is its ease of use and a wide range of cure schedules.Is powder coating worth the money? ›
In many instances, powder coating is the superior finishing option for its durability, texture and ease of application. It can stay on for years and protect your parts from corrosion and rust. Powder coats look good in any home and offer a much safer application process than spray paint.
Can I powder coat aluminum at home? ›
Although we hear the term often, not many people really understand what powder coating is, and fewer realize the process can be done at home with great results. Powder coating is stronger than solvent-based paint coatings, takes very little training or practice, and the cost is very competitive to paints.Is it better to paint or powder coat aluminum? ›
Aluminium powder coating is usually the desired solution, as it offers a number of advantages over wet paints. For example the powder coating ensures that a strong layer is formed over the aluminium.What temperature can you powder coat aluminum? ›
It is reasonable to cure powder coatings on the 6061 aluminum alloy with temperatures ranging from 120 to 210 °C and at any time frame less than or equal to 30 min, without degradation to the mechanical properties of the alloy.How thick is powder coating on aluminum? ›
Even though powder coatings commonly exhibit a natural wavy appearance that suggests they may be thick, the typical powder coat layer is less than 1/10th of a millimetre thin (< 100 µm).