We live in a world of dirt, oil, and human error. As finishers, it’s good to acknowledge these realities. The sooner we embrace the inevitability of rework, the sooner we can get to problem-solving.
Here are the three most common rework scenarios I see at Kaser, and what to do about them.
Where there are fish eyes, there is oil. It’s just a matter of figuring out whether that oil is on the substrate, or in your air supply. If every single part in the order is having the same problem (especially if other orders are not), it’s likely that your pretreatment process was insufficient for those parts. The substrate is probably still greasy. You’ll want to beef up your pretreatment process and try again.
On the other hand, if the first couple of carts came out fine but you suddenly have fish eyes, it could be your air supply. Change your filters and spray a test part to know for sure.
Dirt and debris make for unwanted texture in powder coated finishes. If you’re experiencing lumps, bumps, and crunchiness, you have to determine whether that debris is coming from your facility, or the box of powder itself. Start by looking at your equipment. Are the carts and crossbars shedding debris onto your parts? When’s the last time you swept the floors and oven? Is there a fan somewhere, blowing dust around the shop?
If you’re dealing with a high volume of debris on every angle of the part, it’s likely that the powder itself is contaminated. Start by verifying that your powder stock is stored securely in undamaged boxes. If so, it’s possible that something went wrong at the powder manufacturing facility – perhaps a foreign object fell into the extruder, resulting in specks of non-powder material strewn through the whole box. Spray some sample panels for confirmation.
There’s nothing worse than pulling a batch of white parts out of the oven, only to notice that they’re covered in tiny red specks. If the colors you’re seeing are colors you’ve sprayed recently, your color change process likely needs revamping. Sweep and blow the booth down thoroughly. Clean your gun. Change your PPE. If you spray a lot of white, dedicate a hose, pump, and a pickup tube to that color.
If you’re seeing specks of a color that you haven’t sprayed recently, it’s possible the powder was contaminated during production. Perhaps the production line didn’t discard enough powder between colors, and the previous run’s color snuck into your box.
Pro tip: always check yourself before accusing your supplier. Once you’ve eliminated all possibilities of user error or contamination in your shop, then contact your sales representative for assistance.