Powder Coating Process
For effective powder coating there are three basic steps that Classic Custom Coatings performs:
- Part preparation or the pre-treatment
- The powder application
Part Preparation For Powder Coating
Proper preparation is the basis of any good coating. Most powder coating failures are due to a lack of an adequate preparation so the experts at Classic Custom Coatings will take the time to prep your piece properly. Different materials require different pre-treatment methods.
First, the part to be powder coated undergoes a standard degreasing. Then, the old finish is removed using abrasive blasting like sandblasting, plastic, or glass bead blasting, depending on the type of metal, and the finish to be removed. Thin, soft, delicate metals get plastic blasted while sandblasting or glass bead blasting are used on harder metals, rust, and tougher finishes. All rust and old finish must be removed, even the clear coat that factories often apply to polished pieces.
Next, the part is dipped in a chemical cleaner that will remove any other contaminants and residue of previous processes.
Then, the part is hung and prebaked in the oven for slightly longer, and at slightly higher temperatures than the final powdered bake. This causes ‘outgassing,’ or the expelling of any gasses remaining in the pores of the metal. This step is necessary to avoid any bubbling, blistering, or peeling in the final powdered finish.
Finally, the part is moved to and hung in the spray booth as soon as it has cooled from the pre-bake to prevent dust from attaching. Since the booth is electrically grounded, so is the part that is now ready for powder coating.
The Powder Application
Applying the powder coating to metal objects is done by spraying the powder using an electrostatic gun.
The powder receives a positive electric charge and is then sprayed towards the object, which is grounded. Through the application of heat and energy, the metal part attracts the powder like a magnet.
Once the proper amount of powder has been applied, the object is then baked at about 375-400 degrees for 15-20 minutes.
During this time, the powder adheres to the metal part until it melts and fuses into a uniform, hard coating.
Finally, the piece is removed from the oven and allowed to cool. The resulting powder coating creates a tough, durable finish in a variety of surface treatments that will outperform conventional paint.