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Axalta Powder Coating Systems Nordic AB
Box 520, Södra Varvsgatan 23
SE-593 25 Västervik
Sweden

Checklist for a problem-free powder coating process

Specific characteristics metallic powders


Insufficient levelling, rough surface

Identification

Possible cause

Remedial action

From insufficient film thickness to finely textured surface Insufficient deposition Increase high voltage, check spray nozzles
  Output of powder too low Increase powder flow
  Blowing-off effect Reduce amount of air
  Flow of powder too high, together with low application voltage Reduce powder output, increase voltage
  Insufficient charging during tribo application Use appropriate charging method (corona charging)

Colour variation

Identification

Possible cause

Remedial action

"greying", missing metallic effect Wrong or different charging procedure, hence a different alignment of metal effect pigments Corona charging recommended, standard application procedures need to be used for each powder
Objects do not match in terms of colour or effect Powder being used is not correctly bonded and cannot be reclaimed; results in separation of powder base and metal effect pigments Use powder that can be reclaimed (bonded), ensure that the ratio of virgin powder to reclaim meets the powder manufacturers recommendations; motto "Stop messing about with half measures, and do the thing properly."
    Use powder "spray to waste" (costs, disposal)
  Batch change during a job Use same batch of powder during a single job
  Powder separating in powder hopper Use fluidised bed hopper to avoid partial separation
Objects do not match in terms of colour or effect Colour differences between automatic and manual coating process If possible, do not use manual coating after automatic application but do any manual coating prior to automatic application
  Different substrates Produce colour standard and colour tolerance standards for different substrates
  "Differences" with the customer regarding the colour Agree upon colour standard and agree tolerances confirmed by standard panels

Clouding

Identification

Possible cause

Remedial action

Appearance of irregular light dark effects on substrate Wrong space between sprayguns, different charging, improper sine curve, insufficient earthing Optimise coating plant parameters
  Obviously different film thicknesses Minimise variations in film thickness
  Automatic coating process with subsequent manual application Use manual pre-coating where manual reinforcement is required