Troubleshooting guide for zinc phosphatizing

Problem, Cause and Remedy

Coating weight too lowPhosphate or accelerator concentration too low.Increase concentration
Temperature too lowRaise temperature
Process time too lowLengthen time
Coating weight too highPhosphate or accelerator concentration too highDecrease concentration
Process time too longShorten time
Powder on coatingPoor rinses.Keep rinse overflowing
Excessive sludgeDe-sludge tank
Accelerator concentration
too high
Allow concentration to drop
Spotty coatingPoor cleaningCheck cleaning tank
Low concentration of phospha-tizer or acceleratorIncrease concentration
Poor solution coverageCheck racking and nozzles
Resistant metalAdd Jernstedt salts to rinse or to cleaner tank
RustingCoating weight too lowSee “Problem-Coating weight too low.”
Final dry-off too slowIncrease temperature in the fiial rinse-use air blow-off
Dry-off between stagesBetter placement of nozzles.
Use fog nozzles.
Run at lower temps.
StreakingPoor cleaningCheck cleaning stage
Poor rinsingKeep rinses over-flowing
Dry-off between stagesBetter arrangement of nozzles.
Use fog nozzles.
Run at lower temps
Toubleshooting guide for zinc phosphatizing

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