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Durapass 741

Product description

Durapass 741 is a liquid product formulated with
chromium trioxide and other additives suitable for
post treatment of iron, steel, zinc, and aluminum.


  • Durapass 741 helps in preventing the corrosion
    attack on substrate by passivation the surface thus provides sufficient safe time for powder coating or any other suitable final finish.


  • Durapass 741 passivation gives temporary corrosion protection to substrates after phosphating, cleaning or etching.
  • Durapass 741 is suitable for immersion and spray
    systems and provides extra resistance against corrosion. Improves adhesion and minimizes under
    film blistering of final finish.
  • Durapass 741 is most suitable product for post treatment after iron phosphating, zinc phosphating
    and etching for substrates like iron, steel, galvanized
    steel and aluminum.

Physical & Chemical Properties

Appearance :Liquid.
Color :Dark red brown
PH (1%) at 250C: 2.85 ±0.25 at 250C :1.43±0.05
Total Acid point (1%): 8.5 ± 0.5 (0.1N NaOH)
Miscibility in water: Miscible at all ratios.


The main process tank can be fabricated from stainless steel or acid resistance material tank is recommended for durability.

Process Sequences

  •  Zinc plating Process (Acid/Alkaline)

  • Passivation with Durapass Zinc Dip.
  •  DI Water Rinse.
  • Drying

Operating Parameters

Concentration (ml/1000 liter) :150 to 500
Total acid point: 1.2 to 4.5
Temperature(0C): 20 – 45

Time (sec) :30 – 90
Pressure (Bar) :0.5 to 1.0

Process Sequences

  • Cleaning surface from grease, oil and dust.
  •  descaling with Dura pickling liquid
  •  Passivation with Durapass SS
  •  Hot water Rinse.
  •  Drying

Initial preparation:

  • Add 150 to 500 ml of Durapass 741 per 1000 lit of operating volume.


  • A continuous over flow should be maintained to
    avoid contamination of rinsing bath.
  • It’s desirable to maintain the bath with D.I water to
    avoid salt residue.
  •  PH should be checked frequently to keep it with in
    above -mentioned limits.

  • Titration point should be checked regularly.
  •  If titration point is within the limit and pH is not under control then bath should be discarded.