Acid etching baths are used for oxide removal and cleaning of the surface of different types of steel. To keep the bath in an optimum condition the Fe2+/Fe3+ and free acid/total acid ratios must be maintained within certain limits. Auxiliary substances like hydrogen peroxide are added to influence the Fe2+/Fe3+ ratio, which is responsible for a constant activity of the bath.

The quality of the end products depends directly on the correct composition of the etching bath. Keeping these parameters in an optimum range results in a permanently higher quality and at the same time lowers costs due to lower reagent consumptions.

This bulletin describes the monitoring of an etching bath in the steel industry. ProcessLab offers a solution that automatically evaluates the desired bath parameters (free acid, total acid, Fe2+ and Fe3+). Due to the flexibility offered by ProcessLab the determination of hydrogen peroxide can be integrated very easily.


Metrohm AG

9100 Herisau