Modern Metal Finishing: Choosing Between Powder Coating and Spray Paint

If your business involves in metal finishing work or producing parts, tools or equipment that incorporates metal finishing, you may have this dilemma sooner or later: Should you use powder coating and spray paint? If you are a metal finisher or business owner who’s still considering the right methods, here’s a simple guide for you.

So, as you might have already known, spray paint is by far the most popular means of protecting metal, but it isn’t the only way to keep everything from cars to outdoor lawn furniture protected from the elements. In fact, spray paint may not even be the ideal way to protect metal against corrosion.  That said, is there any other alternatives?

Powder coating in a special camera

If you must choose one, the popular alternative to spray paint is powder coating. While powder coatings can require more specialized equipment to apply, they generally offer superior protection and longevity.

Here’s a look at the relative benefits of powder coating.

Powder Coatings Are Harder

Once a powder coating is fully cured, it will be substantially harder than traditional paint and thus more resistant to scratches and chips. How so?

Well, powder coatings typically exceed the finished performance characteristics of conventional solvent-based paint coatings by at least one order of magnitude. In particular, powder coatings are more resistant to cracking and peeling and also provide high abrasion, corrosion, and chemical resistance.

Flexibility Is Outstanding

Compared to paint, powder is extremely flexible. In fact, powder coatings applied to tinfoil can be crumbled and flattened without any flaking, cracking, or compromise of hardness. Powder coatings are highly flexible because they are polymers – a substance consisting of mostly or entirely similar materials that are bonded together.

Color and Texture

In terms of the sheer number of colors available, spray pink probably has a slight advantage. That said, powder coatings come in a vast variety of different colors and sheens.

Powder coating

For the most part, the range of colors available for powder coatings is extensive enough that most people can easily find a color to perfectly match their requirements. An example of the vast range of color options for powder coatings is available from Reliant Finishing Systems.

In terms of texture, the options available for powder coatings are generally more extensive than those available for spray paint. In addition, because powder coatings are more durable than spray paint, adding intricate texture doesn’t compromise the quality of the coating as it does with paint.

What Can Be Powder Coated?

Any metal object that can hold an electrostatic charge can be powder coated. In addition, metal must be able to tolerate the high levels of heat necessary for the curing process to take place. Examples of metals that are frequently powder coated include mild steel, galvanized steel, electroplated steel, stainless steel, and aluminum. Most steel alloys can also be powder coated. Advances in powder coating now allow the polymer to be applied to wood in some cases.

In many cases, people are concerned that powder coatings cannot be applied to surfaces that have sensitive areas like threading or clearance holes that cannot be painted. In truth, special high-temperature masking can be applied to almost any surface that can be powder coated in order to prevent the coating from adhering. Additionally, high-temperature plugs made of silicone can be used to protect threaded holes, shafts, and other clearance holes that should not be coated.

There Are Multiple Options

Though the term powder coating is applied to any process using an electrostatic coating, there are actually four different types of powder coating to choose from. Just as with spray paint, different chemicals can be used in powder coating to provide different levels of hardness, flexibility, chemical resistance, corrosion resistance, and more.

Powder coated wheel rim
Powder coating on wheel rim – before (left) and after (right) – image via Wikimedia Commons

General options for powder coating are as follows:

  1. Epoxy is very hard, highly flexible, resistant to chemicals and corrosion, and cures at relatively low temperatures. Epoxy coatings are not recommended for exterior applications.
  2. Polyurethanes are valued for their flexibility and thus are preferred for use on moving parts. Polyurethanes provide excellent exterior stability.
  3. Hybrid, which consist of epoxy and polyurethane blends, are generally recommended for their high levels of chemical and solvent resistance. Hybrid coatings are not quite as hard as epoxy coatings but offer excellent flexibility and are easy to apply.
  4. Polyester coatings are valued for their exterior stability and performance. They are also highly flexible and the most forgiving when used by beginners.

An Eco-Friendly Option

Spray paint actually isn’t all that good for the environment. In particular, the solvents used to keep the paint liquid until they are applied to a final surface can be damaging to air quality. Powders, on the other hand, do not require any solvents. In fact, there are almost no health threats to being in contact with the powder used for powder coating

Overall, powder coating requires just a simple mask to be worn to prevent inhalation of the powder and does not require high-level respirators that are absolutely necessary with some of the more durable spray paints such as urethanes.

So, will you use powder coating for your metal finishing? Please share your thoughts.