BYK 1640 is a polymer-based, VOC- and silicone-free defoamer suitable for aqueous systems. BYK 1640 exhibits optimum performance at the lowest dosage, is stable to acids and alkalis, and can be used in the pH range 3-12. BYK 1640 has a spontaneous defoaming effect and is also suitable for preventing microfoam. BYK 1640 defoams and simultaneously inhibits the formation of foam, both during production and application. As a result of its approval for use in contact with food, BYK 1640 can also be used in systems which are to come into contact with food. BYK 1640 offers an effective and alternative solution to common defoamers.