Powder coating is an excellent finishing option for both interior and exterior-use metal. Whether it’s a car, a motorcycle, or a piece of patio furniture, a powder coat finish can add the crowning touch of style to your metal item while helping to protect it from the elements.
However, what if you’ve noticed that your powder coat is developing white or chalky spots, or is deteriorating in some other way? Has your powder coat possibly been affected by the changing of the seasons? Or maybe you are thinking about applying a new powder coat to a piece of outdoor furniture. How can you ensure that your powder coat will stay durable under changing weather conditions? The following information will provide answers to those questions.
How Changing Seasons can Affect Your Powder Coat
There are many environmental factors that can cause an applied powder coat to begin to deteriorate. Here are four important determinants in this process:
An ideal temperature range for powder coat storage would generally be between 68 to 80 degrees Fahrenheit. However, very few spots on the planet have a climate consistent enough to accommodate such a temperature range all year long. For instance, Las Vegas has highs in the 100’s during summer days, and lows in the 20’s during winter nights. This means that indoor storage of your coated parts may be required for optimal conditions.
Additionally, high levels of UV radiation can, over time, cause both a huge reduction in gloss and color washout of perhaps 50% or more. This is why standards of powder coat outdoor durability typically use climate conditions found in South Florida, central Arizona, or Okinawa (for Japanese regulations) as measures of product performance.
High humidity levels can also have a negative impact on powder coating durability and appearance. Before the curing process has been completed, powder coats in humid areas may pull in and trap moisture from the surrounding air. This will ultimately lead to a discolored, “stained” appearance in the finish.
For stored parts that already have an applied coat on their surface, a humidity range between 47 to 55% is typically ideal.
Powder Coat Quality
There are different levels of quality among powder coats. The most basic measure of a powder coat’s performance with regards to outdoor durability is referred to as industrial or entry-level architectural grade. This type of powder coat would generally maintain its gloss and color consistency for 12 to 18 months in South Florida weather conditions.
On the other hand, there are powder coats that boast exceptional outdoor durability, such as high performance exterior durability grade coats, and exterior automotive grade coats. Depending on the specific product, these powder coats can withstand 5 to 10 years of South Florida-like climate conditions without exhibiting significant degradation.
Powder Coat Type
It is important to note that when it comes to outdoor applications, not all powder coats are created equal. In fact, certain types of powder coating are not well-suited for exterior usage.
Here are four powder coating types, along with a brief description of their suitability for outdoor application:
- Epoxy. Epoxy-based powder coats have excellent corrosion resistance properties. However, sunlight and other weather conditions can quickly cause their appearance to deteriorate – perhaps within a matter of months.
- Polyester. These powder coats offer good resistance to UV radiation, chemicals, and corrosion.
- Urethanes. Very similar to polyester, urethane powder coats are less flexible than their counterpart, but more resistant to chemicals.
- Fluoropolymers. Fluoropolymers have exceptional weathering capabilities, and can retain gloss and color consistency for long periods of time. In some cases, they can retain their appearance for decades. While other types of powder coating may be less expensive, or suitable for unique applications, fluoropolymer-based powder coats are clearly superior for outdoor use.
How to Finish or Refinish with a Weather-Resistant Powder Coat
What is the proper way to apply a high quality, high performing weather-resistant powder coat to your metal materials? The application process follows three basic steps:
- Sandblasting. Sandblasting, more properly referred to as media blasting, is the sanding process that strips away all paint and surface contaminants from the metal material. Sand or other particles are blasted towards the workpiece via a stream of compressed air. This is the vital preliminary step that precedes the actual application process.
- Applying. Before the actual powder coat is applied, primers and rust deterrents are usually set on the surface as a foundation. For instance, an iron phosphate pre-treatment followed by a zinc-rich primer can help to prevent rust from developing in the future. Then the actual powder coats are applied on top of the rust deterrents, and they stick to the material’s metallic surface due to electrostatic charge.
- Curing. The curing process is an often misunderstood part of a powder coating project. In order to successfully cure a powder coated object, it is necessary to expose it to intense heat, usually by baking it in an oven. The exact temperature and length of time the object will stay in the oven depend on several factors, such as the type of powder coat and the object it is covering. Under-curing and over-curing are two common mistakes that inexperienced operators make during this final phase of the powder coating process, which is why it is so important to follow the exact specifications that an accurate cure schedule can provide. Upon completion of the baking process, the object will likely need to be stored away from potentially damaging weather conditions until it has been completely cured.
Applying the correct type of powder coat for outdoor use is essential to its durability and longevity. The sandblasting, application and curing process is also crucial to the ultimate success of your project. In the end, metal materials that undergo proper powder coating enjoy a better and longer-lasting appearance.
If you are searching for a way to maintain that “brand-new” look for your outdoor furniture, auto parts, or other metal materials, then search no further than our experts at AR Powder Coating. Let our skilled technicians apply the most weather-resistant finish available to your metal items. Then that powder coat finish can remain your car, motorcycle, or patio chair’s crowning touch for years to come.