Sodium Carbonate Moyen Cleansing Agent Régule le sébum Sodium Carbonate at a glance Highly alkaline salt pH adjuster Ruled safe in small amounts in cosmetics Also called soda ash or washing soda Sodium Carbonate description Sodium carbonate, sometimes called soda ash or washing soda, is a highly alkaline (basic) inorganic salt. Sodium carbonate has many industrial uses, primarily in glassmaking. In cosmetics, its primary function is as a pH adjuster. Sodium carbonate’s alkaline nature is damaging to skin in higher amounts, so it is only used in leave-on products in very low amounts, typically from 0.0002-0.044 %. The independent Cosmetic Ingredient Review panel has ruled that sodium carbonate is safe in its current usage in cosmetics. Related ingredients: Sodium Bicarbonate