With our decades of experience comes the knowledge on how to solve common powder coating challenges:
1. The Challenge: Faraday Cage Effect – when a product is shaped in a way that inhibits the electrostatic application of the powder from a particular area, curve or recess. It often occurs when spraying into a part’s corner, and it’s one of the common challenges powder coaters face.
The Solution: Sometimes, the metal piece is preheated so that it allows the powder to stick more quickly. This is not ideal, however, because heat attracts powder like a magnet and you could end up with a powder coat that is too thick.
A better solution is to adjust the amperage and voltage from gun tip to the part. (Static is turned up, powder turned back). Millage tests are done to ensure proper coverage.
If parts don’t pass the millage test, the powder is burned off and parts are blasted again to redo.
2. The Challenge: Water Traps & Pinholes – In a pretreatment process, metals undergo a prewash to ensure a clean substrate. Sometimes, though, that water might not evaporate in a weld. Even a tiny droplet, when hidden under a powder coating, can become a huge mess once it hits the curing oven.
The water will boil out of the pinhole and create a mess. A small air pocket can do the same kind of damage.
The Solution: Manufacturers should be sure to have tight, solid welds without pinholes to avoid water damage. Otherwise, the visual appearance and timeline may be compromised.
Patch the pinhole, sand it and recoat. Careful, on-line inspections are crucial.
3. The Challenge: Unclean Substrate – Any sort of contamination between substrate and powder will compromise the bond.
The Solution: Manufacturers should be sure the proper steel grit and/or sandblasting is removing weld smoke or weld splatter before the product is powder coated. Metal parts should undergo a proper washing and rinsing system beforehand.
4. The Challenge: Spray Room Contamination – Going from one color to another can result in tiny specks of an unwanted color on a run.
The Solution: Proper cleaning procedures, especially if the powder is being reclaimed. Changeover clean-down needs to include the entire system, spray guns and their components.
5. The Challenge: Impurities in the cast – Sometimes there are impurities in the cast itself that will come out through the coating. Those impurities are in the metal itself, so they’re not visible beforehand.
The Solution: Keystone Koating can preheat the metal to get out impurities, or use different primers before powder coating. Parts with such impurities may need to be run through the line twice.
6. The Challenge: Leeway time – Mostly an issue when a custom powder coating color is requested.
The Solution: Allow 1 to 3 weeks for a custom color for parts, or choose a stock powder nearest to the desired color for quicker turn-around.
7. The Challenge: Not all powders are alike – there are different types of powders, some hammer tones, wrinkles and veins, some need to be sprayed heavily; some sprayed lightly.
The Solution: A coater who has experience with application of the various powders.