Trivalent chromium black passivation for chloride bath


  • Contains trivalent chromium and produces a more appealing black appearance compared to conventional agents.
  • Ideal black passivation for zinc plating in chloride bath.
  • Extended service life is achieved compared to conventional passivation agents.
  • Corrosion resistance is greatly improved compared to conventional products, with a general corrosion resistance of SST192hr.
  • Does not contain silver or dyes.

The benefits described above are results obtained at YUKEN, and performance in the customer environment should be verified separately.

Product Specifications


Appearance Dark blue strongly acidic liquid (METASU YFB-NAA)
Red strongly acidic liquid (METASU YFB-NBA)

Bath makeup conditions

Chemicals used Usage range
METASU YFB-NAA 20 – 60ml/L
METASU YFB-NBA 60 – 100ml/L

Usage conditions

Item Range Remark
Process temperature 30 – 50°C
Process time 40 – 90 seconds
pH 1.8 – 2.5 Verify pH value before usage. Adjust using caustic soda or hydrochloric acid if the pH value falls outside of the specified range.
◎ The pH value must be adjusted to 2.2 during bath makeup.
Agitation Yes In the case of basket processing, use vibratory agitation.
In the case of rack processing, use air agitation or vibratory agitation.

Replenish conditions

Chemicals used Replenishment reference (standard)
METASU YFB-NAA 5 – 20ml/100dm2
METASU YFB-NBA 40 – 80ml/100dm2
Synthetic hydrochloric acid pH adjustment

Adjust the pH value to fall within the specified range.


Inquiry about the product

Feel free to contact us if you have any questions or matters to discuss.