Defoamer based on a stabilised copolymer dispersion. Product does not contain silicone oils of the type dimethyl siloxanes. DEFOAMER 45 can be applied in cutting fluids, lubricants for wire-drawing and other metal forming operations, in degreasing agents, in formulated chemical products, in waste-water treatment and in other processes where effective defoaming is needed without the use of silicone oils. Product is stable in the pH-range 6-11. It will not adsorb to metal surfaces. The life of the defoamer is prolonged, and adhesion problems during the following surface treatment due to defoamer residues will not appear. For use in cleaners and metal working fluids, 0.1-2.0% of DEFOAMER 45 is added to the concentrate depending on product type and the demand for fast defoaming action. DEFOAMER 45 may also be added to the diluted product.