Shampooing in other countries began in the early 1930s. Before shampoo, people mainly used soap, detergent, and laundry powder to clean their scalp and hair. Later, coconut oil soap was used to make liquid shampoo. However, soap-based shampoos had many drawbacks, especially in hard water. Soaps made from potassium fatty acids would form sticky precipitates when they encountered calcium and magnesium ions in hard water, leaving residue that was difficult to rinse off the hair. Furthermore, soap-based shampoos left hair sticky, dull, and difficult to comb.
In the early 1940s, liquid emulsified shampoos and cream emulsified shampoos made from sodium lauryl sulfate were introduced. Compared to soap, shampoo has several advantages: stronger lathering and cleaning power, producing rich foam even in hard water; easier rinsing without leaving unnecessary sediment or residue; and gentler than soap products.