Rough coating

(1) Excessively high temperature

(2) High zinc content

(3) Turbid solution

(4) Insufficient citric acid or   ammonium chloride

(5) Insufficient brightener/softener

(6) High impurity content

(1) Lower the temperature

(2) Reduce zinc anodes

(3) Filter the solution

(4) Adjust the content per analysis

(5) Replenish brightener/softener   appropriately

(6) Treat and filter the plating   solution

Poor throwing/covering power;   distinct anode/cathode surface difference

(1) Insufficient complexing agent

(2) Small anode area

(3) Low cathode current density

(4) Insufficient polyethylene glycol   or softener

(1) Replenish per analysis

(2) Increase anode area (graphite can be used)

(3) Raise cathode current density

(4) Replenish polyethylene glycol or softener as appropriate

Pinholes, pitting, and streaks in   coating

(1) Insufficient seagull detergent or   softener

(2) Heavy metal contamination

(3) Excessive organic impurities

(1) Add 0.1 mL/L detergent or replenish softener

(2) Treat with zinc powder

(3) Activated carbon treatment

Brittle coating

(1) Excess brightener

(2) Excessively high current density

(3) High metallic impurity content

(1) Activated carbon treatment

(2) Reduce current density

(3) Treat with zinc powder

Slow deposition rate; partial lack   of coating

(1) Poor pre-plating treatment

(2) Excessively low current density

(3) Poor electrical conductivity

(4) Small or unevenly distributed anode area

(5) High carbon content of parts

(1) Inspect and improve pre-treatment

(2) Increase current density

(3) Inspect contact points of conducting rods and hangers

(4) Adjust anode area and layout

(5) Apply high-current strike at the beginning

White and dull coating; poor   passivation brightness

(1) Insufficient thiourea or main brightener

(2) Excessive organic impurities

(1) Replenish thiourea or main brightener

(2) Activated carbon treatment