From the mid-1920s, BYK launches finishing agents for paint production, including special plasticizers and the anti-settling agent ANTI-TERRA. Solactol is becoming one of the first star products in the field of paint auxiliaries. BYK advertises the lactic acid ester as an "indispensable aid in paint production".

The painting auxiliary is particularly useful in the production of aircraft paints, but can also be added to insulating, wood and bottle paints as well as protective paints for labels and cigarette mouthpieces. The paint finishing agent is available in carboys, aluminum cans and aluminum barrels.

The competition soon becomes aware of the successful paint auxiliary: A large chemical company procured Solactol through an intermediary and examines it in the laboratory. But all attempts to copy BYK's product failed.