How It Works
What is Powder Coating
Powder coating is a type of coating typically applied as a free-flowing, dry powder. The primary technical difference between conventional paint and powder coating is that powder coating does not require a solvent to keep the binder and filler parts in a liquid suspension form. The powder is primary applied electrostatically and is required to be cured at temperatures typically between 315 – 400 degrees Fahrenheit for approximately 10 – 20 minutes. This heating process allows the powder to flow and form a uniform layer over the part being coated. Powder may be thermoplastic or thermo set polymer and each powder has its own specific properties and curing schedule. Powder coating is used to create a hard finish that is tougher and more environmentally friendly than conventional paint. Powder coated parts stay brighter and more vibrant over time than traditional painted parts.
Powder coating is primarily used for coating metals, such as steel, aluminum, brass, copper, alloys and generally speaking any other conductive material that can handle the high over temperatures required to flow and cure powder coatings. Powder coating is available in a full array of colors, textures, and sheens to meet any need. In addition, metallic, candies, clear, iridescent, hammered and multiple layers can be employed to create truly unique finishes. Typical items routinely coated include fences, gates, table bases, patio furniture, tool racks, toolboxes, trellises, outdoor art, indoor art, lamp posts, mail boxes, light fixtures, plumbing fixtures, stair stringers, stair treads, house numbers, shelves, shelve supports, dressers, desks, bar stools, ladders, grates, doors, door hardware, outdoor signage and posts, lockers, wagons, metal toys, picture frames, gym equipment, bicycle frames, motorcycle, ATV and auto parts (frames, roll bars, roll cages, brackets, wheels, bumpers, brush guards, brake calipers, value covers, oil pans, air cleaners, intakes, skid plates, luggage racks, shifters, hitches, receivers, running boards, rock guards, tow hooks, etc.), as well as many other residential, commercial, and industrial applications.
In order for powder to adhere properly, a stringent multi-step process must be followed. The below steps are a brief synopsis of what is required to apply a high quality powder coat finish.
The material must be stripped of any paints or solvents and or sandblasted* to remove impurities such as rust or corrosion, contaminants, cutting lubricants, oils, greases, dirt, previous finishes, etc. This process leaves the part clean which allows for an optimal surface for the powder to adhere.
* Sandblasting (including bead, soda, water blasting) is a generic term used for the process of cleaning a hard surface by forcing solid particles across that surface at high speeds; the effect is similar to that of using sandpaper, but provides a more even finish.
All parts go through a chemical cleaning and pretreatment process where an environmentally friendly chemical is applied to inhibit corrosion subsequent to the part cleaning process and aid in the bonding process. Corrosion is metal’s and powder’s worst enemy, therefore, J&J Powder Coating takes special care to ensure this step is done correctly, as it is fundamental for a superior protective coating for aesthetics and corrosion control.
The part is pre-baked to ensure it is fully dried and to help with powder adhesion to difficult areas of the part (e.g. inside corners, sharp edges).
After the part has been cleaned and prepped for powder, any areas where powder should not be applied are masked off with high temperature tape or are plugged or covered with silicone plugs and caps designed for use in the powder coating process. Great care is taken to ensure that these areas are protected properly (e.g. bolt threads, mounting surfaces).
The part is then moved to a spray area where a special spray gun provides a positive electrical charge to the powder. The gun sprays the powder on the part that has been grounded (negative charge) using an earthen grounding rod. This allows for the powder to “stick” electrostatically to the part. (Electrostatic powder coating gets its name because the powder particles are forced mechanically or by compressed air through a gun that gives the particles a uniform positive charge.) The charge helps these powder particles spread evenly on the part.
The part is moved to a specialized oven where the powder coating is allowed to melt into the surface of the part allowing for proper adhesion. The temperature is dictated by the type of powder in conjunction with the particular part.
After the part is removed from the oven, they are allowed to cool.
After the cooling stage, we thoroughly inspect the part to ensure that the powder coating does not contain any defects in coverage, color, or visual effects.
After the part has been inspected, we prepare them for shipping, delivery, or pick-up. We utilize various packing materials to help ensure the part reaches the destination as intended.
Great care is required for each of the steps to ensure that the end result meets and exceeds expectations. The average time to complete a typical project is 5 to 8 business days as this cycle time affords each of the above steps to be completed properly.
Powder coating has several advantages over traditional painting methods. The process contains no solvents and releases little to no VOCs. Powder coatings can produce much thicker coatings than conventional liquid coatings without running or sagging. Powder coated items generally are more uniform in appearance than liquid coated items especially between horizontal surfaces and vertical surfaces. A wide range of specialty effects (textures and sheens) are easily accomplished using powder coatings that would be difficult or impossible to achieve with other coating processes. Curing time is significantly faster with powder coating than with liquid coating. Parts that have been powder coated are more resistant to chipping, scratching, fading, and general wear and tear than conventionally painted parts.
The primary disadvantage is that ultra-thin coats are very difficult to achieve. If ultra-thin coats are required, conventional paint is a more suitable solution.