Trouble Shooting Guide

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Problem:
Coating weight too low

Cause(s):

•   Phosphate or Accelerator concetration too low
•   Phosphate bath temperature too low
•   Process time too slow


Remedy:

•   Increase concentration
•   Increase phosphate bath temeperature
•   Lengthen time phosphating stage

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Problem:
Coating weight too high

Cause(s):

•   Phosphate or Accelerator concentration too high
•   Process time too long

Remedy:

•   Decrease concentration
•   Shorten time

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Problem:
Powder on Coating

Cause(s):

•   Poor rinses
•   Excessive sludge
•   Accelerator concentration too high
•   Higher bath temperature

Remedy:

•   Keep rinse overflowing
•   De-sludge tank
•   Allow concentration to drop
•   Lower the temperature of the bath

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Problem:
Spotty Coating

Cause(s):

•   Poor cleaning
•   Low concentration of Phosphatizer or Accelerator
•   Poor solution coverage
•   Resistant to Metal

Remedy:

•   Check cleaning tank
•   Increase concentration
•   Check racking and nozzles
•   Add Jernstedt salts to rinse or lean tank

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Problem:
Rusting

Cause(s):

•   Coating weight too low
•   Final dry-off too slow
•   Dry-off between stages
•   Higher free acid pointage in phosphating bath

Remedy:

•   See "Trouble Coating Weight too Low"
•   Increase temperature in the final rinse using air blow off
•   Better placement of nozzles
•   Use fog nozzles
•   Run at lower temperatures
•   Reduce the free acid pointage

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Problem:
Streaking

Cause(s):

•   Poor cleaning
•   Poor rising
•   Dry-off between stages

Remedy:

•   Check cleaning stage
•   Keep over-flowing
•   Better arrangement of nozzles
•   Use fog nozzle
•   Use fog nozzle
•   Run at lower temperatures

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Links in this section:
• epoxy polyester powder • epoxy powder • polyester powder
• speciality powder • why powder coatings? • household appliances
• automotive components • furniture • architectural • electrical
• metal pre-treatment • chromatising • iron phosphating • zinc phosphating
• chromate process • troubleshooting tips • material safety sheets

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