The stock is pumped and sent tangentially to the top of the cell after being aerated by a set of small auto clean injectors. Once in the cell, air bubbles, after collecting ink particles, rise up to the top of the cell to creat a thick foam mat which is evacuated due to the slight pressurization of the cell. The stock partially de-inked goes to a de-aeration chamber and is pumped full flow to the next stage. The operation is exactly the same as for the first stage, with the same number of injectors and same flow.

The operation is repeated up to five times, thus giving the best possible ink removal under industrial conditions. Re-mixing of the air coming from the downstream stages aids the upper stages significantly improving the overall cell efficiency.