10% (v/v) Antifoam 204 is a ready-to-use non-silicone organic antifoam, prepared as a dilution of Antifoam 204 in purified water. The concentration is defined on a volume-per-volume basis: 10 mL of Antifoam 204 per 100 mL of final dilution. The 440 mL fill in a 1 L bottle leaves headspace to mix before use.

It is commonly used to control foam in sparged bioreactors, fermenters, and shake flasks. The pre-diluted format makes small doses easier to measure accurately, which helps avoid the excess antifoam that fouls downstream filters. Mix well before each use, since the dispersion can separate on standing.