Antifoam 204 is an undiluted organic antifoam made of non-silicone, polypropylene-based polyether dispersions. It is supplied neat for direct dosing or for preparing working dilutions. The 500 mL fill supports pilot-scale bioreactor runs.

It is commonly used to control foam in sparged bioreactors, fermenters, and shake flasks, where foam at the gas–liquid interface damages cells and causes overflow. Dose at the lowest effective concentration, since excess antifoam can foul depth filters and membranes downstream.