Trivalent chromium black passivation agent

METASU YFB-NA7/NB7/RN7 is a trivalent chromium black passivation agent that not only produces an attractive black surface finish, but is also economical as it renders a longer service life.

・It uses trivalent chromium and produces a more enchanting black finish compared to conventional agents.
・It is ideal for blackening of chlorid zinc plating bath.
・Extended use compared to conventional passivation agents, lower replenishment amount (1/2 of conventional type based on our study), and enhances external appearance.

・No white rust and corrosion resistance lasts for 120hr - 168hr.
・Silver and dyes are not used.

Product specifications


Appearance Dark blue strongly acidic liquid (METASU YFB-NA7)
Dark brown strongly acidic liquid (METASU YFB-NB7)
Dark reddish-purple strongly acidic liquid (METASU YFB-RN7)
Colorless transparent acidic liquid (METASU YFB-ND7)

Bath makeup

Chemicals used Usage range
METASU YFB-NA7 40~60ml/L
METASU YFB-RN7 60~100ml/L

Usage conditions

Item Range Remarks
Process temperature 30~40℃
Process time 30-50 seconds
pH 1.8~2.0 Verify pH value before using. Adjust using caustic soda or hydrochloric acid if the pH value falls outside of the specified range.
Agitation 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-NA7 10~30ml/100dm2
METASU YFB-NB7 30~80ml/100dm2
METASU YFB-ND7 1~4ml/100dm2
Blended hydrochloric acid pH adjustment

* Adjust so that the pH value is within the specified range.

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Inquiries about the product

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