During filtration without a filter aid, solid particles rapidly block the surface of the filter. The use of a “pre-coating” agent is recommended to circumvent this problem. The desired product may be the separated solid, the filtrate or both.

In concrete terms, the organic filtering agent is diluted in the filtrate or in water and then deposited on the filter. The pre-coating forms and retains solids, while preserving the flow through the filter medium.

The use of a “pre-coating agent” protects the filter medium from clogging, while preserving a strong flow for a longer period, making removal of the filter cake easier.

If your suspensions contain solid particles, with adhesive or viscous impurities, a quantity of filtering agents are added during the filtration cycle: this is alluviation. Using this solution, the filter cake gradually thickens but remains porous, which allows filtration cycles to be longer.