A new oilfield assembly or refinished piece of furniture might look great as a final product, but there’s a lot of work that goes into making sure its surface is prepared before the coating is even applied. If a substrate’s surface is dirty, the coating will not adhere properly and will ultimately fail. To prevent this from occurring, multiple industry-wide surface preparation standards have been developed to clean and properly prepare different types of metal. Given that there are so many different potential cleaning methods and surface materials, these guidelines benefit the industry by standardizing processes and ensuring the highest possible quality for the client.

The most commonly used and accepted standards were put forward by the Society for Protective Coatings (SSPC) and the National Association of Corrosion Engineers (NACE), both professional organizations operating in the corrosion and coatings industry. These organizations came together to bring the Joint Surface Preparation Standards to the industry. These standards cover a multitude of techniques for preparing surfaces, from simple solvent cleaning (SSPC-SP1) to abrasive blasting using a high-pressure gun that leaves a metal surface “uniformly free of all foreign matter” (SSPC-SP5 / NACE 1).

Note that these surface preparations also create anchor profiles from which the powder adheres to the metal. The more aggressive surface preps will produce a deeper anchor pattern. Typical steel grit blast media will produce anchor profiles between 2-4 mils. Mild solvents and hand-etching will produce less. Recognize that the classification numbers of the surface preparation standards do not necessarily increase with intensity (so read them carefully).

The process of powder coating lends a durable, long-lasting, and environmentally-friendly protection to steel surfaces. In addition to its practicality, this coating is also aesthetically pleasing due to multiple coating passes and flow technology which result in an even, bump-free finish. Importantly, the color of the actual coating is versatile as well, with a good variety of standard colors available according to the RAL powder coating color charts and the associated standards, as well as custom or non-standard formulations to match hard-to-reproduce colors.

In many cases, protective coatings must match a very specific existing color. This may be due to the necessity of matching pre-existing surfaces, strict brand standards, or cases where color is used to communicate safety information in a hazardous environment. In many circumstances, the standard RAL powder coating color charts are sufficient for matching desired colors. Developed in Germany in 1927, the RAL color standard defines over 2,300 colors for use in powder coating applications. Such a standard is useful for both powder coating shops and customers of powder coating services because accurate reproduction is important—every application using a specific color should be indistinguishable. If a specific color is used for one job, it should be consistent with another job down the road using the same specification.

In addition to the colors specified by the RAL standard, many powder coating shops can formulate custom colors. This process, albeit timely, may be important for hard-to-match and non-standard colors due to previous jobs using unconventional colors, or the necessity of exact color matching for branding purposes.

With the increase of environmental regulations making solvent-based corrosion protection expensive and complicated to apply and dispose of, protective powder coatings such as zinc-rich primers offer premium corrosion protection without harming the environment. Zinc-rich primers are considered sacrificial coatings, a subset of protective powder coatings meant to dramatically slow down the process of corrosion if the top layer is damaged. This makes them the perfect coating for steel in highly corrosive environments. Zinc-rich primers are great for use in marine, tanker, or underground environments, all of which are considered immersive environments.

There are two types of zinc-rich primers: inorganic and organic. Organic zinc-rich primers are primers that use binders such as epoxy, polyurethane, or alkyd, etc. More commonly used for highly corrosive environments on oil rig platforms, chemical plants, and more, organic zinc-rich primers require a top-coat to be long-lasting.   

Inorganic zinc-rich primers do not require top-coats in more mild atmospheric environments and provide better galvanic protection overall.  Inorganic zinc-rich primers usually use only silicate as a binder and is applied as a powder using the blast method on “white” metal, metals that are light-colored alloys. This is the type of zinc-rich primer Houston Powder Coaters uses.