Powder Coating as it’s mostly referred to is the process of adhering a non solvent based film to a negatively grounded piece. The film is then heated until the particles melt and flow out into a smooth surface coating. While this technique has been around for many of years, many are still boggled about it’s many of benefits and how to use them to their advantage.
In a builders sense, Powder Coating has many benefits over solvent based coatings. Powder Coating has a incredibly low VOC count (Volatile Organize Compounds) so it is far easier on the eco-system then liquid based. It is also far easier to apply thicker coatings then original solvent based films. Powder Coating overspray has the aspect to be 100% re-used compared to liquid based coatings which are un-recyclable once they leave the hvlp gun. Powder coating equipment is also rather simple in it’s application and curing, so the expenses to run an assembly line is generally less then a original liquid spraying system. Also, the extra thick coating is far more durable then conventional paint, so it lasts consumer abuse far better.
Powder coating can be applied by a variety of techniques, the 2 most likely are liquid transfer and static spray.In a liquid transfer setup, the powder is applied much like a plating is put on a standard piece. The piece is grounded to the power supply unit, and lowered Powdercoating into a heated chamber of water where the pigmented powders are suspended, and a positive current is applied to the liquid which attracts the particles to the negatively charged item dipped in it. Once that is finished the piece is removed and then allowed to dry before going in for curing. The downside to this system is when drying, the part has the risks of getting pollutants into it’s finishing coat, and will leave faults in the finalized project if not isolated from this.
In a static spray setup, the items are attached to a grounded overhead static line, or any type of conducting platform setup the engineer wants to use. A gun powered by compressed air spins the powder coating particles over a positively charged center rod to charge them. These positively charged particles now flow towards and adhere to the grounded piece in the area’s of least resistance, or in simpler terms, where the powder has the least buildup. The only drawback with a static spray setup is the random occurrence of a Faraday Cage effect, where the charged ions can actually prevent powder from entering a recessed edge or the such. This can sometimes be corrected with raising voltage from the powder coating gun, or by pre-heating the items prior to application.
Once the Powder is adhered, curing can take place by a few different combinations of equipment. Many Powders cure when raised to 400 degrees for about 10 minutes. This allows the polymers cross hatch in thermosetting powders for increased durability. It is vastly important that the piece the powder is being applied to at least meets this core temperature so that the powder coat adheres to the piece yielding maximum durability. Various means for reaching this desired temperature include infrared ovens or convection ovens.