The soap makers of the Fer à Cheval soap factory proceed with several washes of the soap paste after its cooking in the cauldrons. This washing step actually consists of a refining of the soap paste. It is carried out through repeated clear water washings that drive glycerol, raw oil impurities, excess soda, and non-saponified fatty acids towards the bottom of the cauldron. At the surface remains the clean and pure soap that will decant for two days.