You may have heard a lot about powder coating, given the popularity of this type of finish. Powder coating is an in-demand dry finishing method that accounts for over 15% of the entire industrial finishing market. Surfaces need to be prepared before a professional powder coating is applied. Sandblasting, also called media blasting, is an ideal means of preparing for powder coating as a professional finish.
DIY sandblasting can be dangerous and is not recommended. The following is for informational purposes only. Use a professional sandblasting service instead of trying to do it yourself.
Why Sandblasting Is a Great Way to Prepare for Powder Coating
For the best powder coating, it’s crucial that the surface being coated has been cleansed. All oils, paint, dirt, corrosion, rust, and damaged plating, including zinc, chrome, and nickel, should be gone from the surface. These substances can create defects in the powder coating finish or even result in the total failure of the coating. The sandblast process easily and completely clears away corrosion, rust, and contaminants.
The primary advantage provided by the sandblast method is that it creates “tooth,” or a profile on the surface. If you imagine using sandpaper on a piece of metal, you’ll probably think of the thousands of tiny scratches the sandpaper will create. These scratches make high and low points in the metal, which provides more surface area for powder coating to adhere to. This is referred to as a profile. A profile lets the powder coating stick to every high and low point, which it can do more effectively than on a smooth piece of metal.
But using sandpaper can be a laborious and tedious task and may not work well with complicated objects. The sandblasting method provides a consistent textured finish all over the surface, in areas where sandpaper can’t reach. If there is no surface profile, powder coating won’t adhere properly and can peel away. This problem is referred to as delamination.
How Sandblasting Works
The sandblast approach utilizes air under high pressure to clear away scale, rust, paint, dirt, or other substances, leaving behind a clean surface of nothing but metal. The sandblasting gun may be put in a sealed cabinet, referred to as a blast cabinet, which contains media and allows for reuse. Additionally, some sandblasting guns and nozzles may be utilized in places other than inside a cabinet, including a blast room or an outdoor location. However, if the sandblasting gun isn’t used in a cabinet, equipment is necessary to protect the eyes, lungs, and skin.
Using a sandblaster requires an air compressor that will provide the necessary high-pressure air. The sandblast method uses a great deal of air, so the compressor will need to be large enough to handle the job.
The sandblasting method uses extremely dry air from the compressor. If the air isn’t dry enough, the media combines with the moisture and creates clogs. Also, for the purposes of powder coating, the surface should be completely clean after it’s been sandblasted. Using air with too much oil and moisture for sandblasting will probably result in finish imperfections.
Siphon Feed Versus Pressure Pot Sandblasting
There are two main kinds of sandblasters, siphon feed and pressure pot. The siphon feed usually resembles a gun and may feature a trigger or a pedal for control with the foot. One of the gun’s two connections is a supply line that brings air from the compressor. The other connection is a media pick-up hose, which is too wide to insert in a container of media. When air goes through the gun, it utilizes what is called a venturi effect to suck the media into the hose and propel it through the gun’s nozzle. The siphon feed is effective and relatively inexpensive.
Those who want a more efficient tool use a pressure pot blaster. It requires less air and sandblasts approximately four times faster than the siphon feed. It is ideal for jobs involving large surface areas.
Sandblasting to prepare surfaces for powder coating finishing is an involved process that is best handled by experienced professionals familiar with safety protocols. Call our team today to discuss your project and to receive a price quote.