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POOR COATING FORMATION IN PHOSPHATING STAGE

CAUSE

pH not in range (see “Poor Cleaning”)

REMEDY

Adjust pH (down with acid, up with Caustic)

Zinc Phosphating

POOR CLEANING IN DE-GREASING STAGE

CAUSE

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

Metal Pre-Treatment

SPOTTY COATING / STREAKING

CAUSE

Contaminaion rinses
Poor cleaning
Poor exposure

REMEDY

Check rinse tanks
See “Poor Cleaning”, Check racking
Check nozzles

RUSTING

CAUSE

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

REMEDY

SOLUTIONS FOAMING IN DE-GREASING

CAUSE

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

General Tips

Chromate Process

POOR PAINT ADHESION

CAUSE

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