Lumps are common enamel defects, which are characterised by rounded raised areas with typically a diameter between 3 to 12 mm.
This phenomena may ocure at both wet & powder enameling processes.
Possible causes for lumps in random order :
- Drips of enamel slip (wet)
- Dried enamel particles falling from equipment and/or tooling (wet)
- Incorrect spray gun settings (wet)
- Worn out gun needle, nozzle or packings (wet)
- Gun spitting (powder)
- Powder deposition on gun deflectors (powder)
- Incorrect fluidity of powder enamel (powder)
- Oversized enamel particles (powder + wet)
See archive for more information about enameling defects.