Top Reasons Powder Coated Surfaces will Chip or be Fragile
Powder coating is a very satisfying process. You clean the part, apply a dry powder and before your eyes it flows out in the oven and adheres to the surface. Powder Coating is an extremely durable finish and can withstand a lot of abuse; much more than traditional liquid paints. Powder does have its limitations though and enough force/damage can even chip properly applied and cured powder. Sometimes you may powder will chip extremely easily or even come off in sheets. This is due to some sort of error in prep, application, or curing. We discuss below the most common causes of powder coating chipping.
- Improper or Incomplete Curing- A lot of powder adhesion issues we’ve run across come from incorrect curing of the powder. Powder coating goes on really easy, but it requires you being pretty strict when following the curing process. Make sure you check the oven and the part itself with an IR Thermometer to make sure that the surface is up to the curing temps needed before taking it out or changing the temperature in the oven for the final bake. Over baking or curing powder can also damage the powder itself; especially if the oven temperature gets too hot for the powder itself. Improper curing of the powder is usually what causes fragile powder that chips with the slightest abrasion.
- Poor Surface Preparation- When powder “bites” it really sticks to the surface and doesn’t let go. But it needs a clean surface to attach; preferably one with some texture or abrasion to give it something to grab on to. We have seen poor powder adhesion caused by poor prep on parts before powder coating. The best practice is to degrease parts, media blast them, clean with PRE Paint Prep, then pre-bake to outgas the parts, and then powder coat. If there are contaminates on the surface it can cause poor powder adhesion or fragile powder.
- Powder Thickness- Believe it or not if you apply too much powder to a part it can cause the powder to build and be more likely to break off in large chips when impacted. We suggest using only enough powder to fully cover the surface. Too thick of powder build can be caused by too high air pressure in the powder coating gun, too many time spent in the same area on the part, or from trying to get hard to reach areas that may suffer from the Faraday Cage Effect. We suggest using a bright LED Flashlight to check for powder coverage and to start with the hard to reach areas first when powder coating.
Hopefully this tips will help you when diagnosing powder coating chipping issues. Unfortunately when you find these to be the issue with your powder adhesion issues you need to remove the powder completely and start over. You can use a media blaster or Down To Metal Paint and Powder Stripper to clean the old powder off. Watch our complete Beginners Guide To Powder Coating HERE and view all our powder coating products HERE.