Trouble Shooting Guide

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Problem:
Poor coating formation in phosphating stage

Cause(s):
pH not in range (see "Poor Cleaning")

Remedy:
Adjust pH (down with acid, up with Caustic)

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Problem:
Poor cleaning in De-Greasing stage

Cause(s):

•   De-greasing in bath
•   Temperature too low
•   De-greasing in bath
•   Concentration too low
•   Poor exposure to cleaner solution

Remedy:

•   Increase the bath temperature
•   Increase concentration of the bath
•   Check racking and nozzles
•   Check pressure
•   Increase the pressure if necessary

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Problem:
Spotty Coating/Streaking

Cause(s):

•   Contaminaion rinses
•   Poor cleaning
•   Contamination rinses
•   Poor exposure


Remedy:

•   Check rinse tanks
•   See "Poor cleaning"
•   Check rinse tanks
•   Check racking
•   Check nozzles

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Problem:
Rusting

Cause(s):

•   Coating weight too low
•   Dry-off too slow
•   Drying between stages


Remedy:

•   Increase the bath temperatures
•   Lengthen time in phosphating stage
•   Increase concentration of bath
•   Increase temerpature in final rinse
•   Run at lower temperatures
•   Better placement of nozzles
•   Use fog nozzles

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Problem:
Solutions foaming in De-Greasing

Cause(s):

•   De-Grease bath temperature too low
•   Pressure too high
•   Pumps picking up air


Remedy:

•   Increase the bath temperature
•   Check for plugged nozzles
•   Check pump packing
•   Check water level

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Problem:
Poor Paint Adhesion

Cause(s):

•   Phosphate Coating too heavy
•   Contamination
•   Bad steel


Remedy:

•   Lower temperature
•   Lower concentration
•   See "Poor Cleaning"
•   Look for source of silicone near washer
•   Check raw material for excessive oil

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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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