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.

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