The cold process method of making shampoo bars requires patience and takes weeks instead of hours for the bars to cure, but it is better for the environment, healthier for your hair, scalp, skin, and body because it is just natural plant-based oils and sodium hydroxide (lye), which is used in the making of the shampoo bars, but not contained in the final product.

During saponification, the reaction between the sodium hydroxide ( lye) and the natural oils forms the shampoo bars. That reaction changes the sodium hydroxide (lye) so that it is no longer present in the bars.