On a continuous pickling unit, after the etching bath, the strip is washed. With a low quality of washing or an insufficient amount of inhibitors, chlorides remain on the surface of the pickled strip after washing and drying, which are provocateurs of technological corrosion. A technology needs to be developed to control residual chlorides on the etched strip surface in the production stream. "1. Type of product - pickled hot-rolled strip: 2. thickness - in the range from 1.4 to 6.4 mm, 3. width - in the range from 860 to 1670 mm, 4. maximum strip speed - up to 7 m/s, 5. temperature of rolled metal - no more than 65 ºC. 6. Measurement error of no more than 0.5 g/m²