Shampoo Manufacturing Plants are typically viscous liquids, either clear or opaque (pearlized), containing 20–40% solids, adjusted to approximately pH 5.5. Most, but not all, have viscosities in the ratio of 500–1500 centipoises. A hair shampoo may be defined as a detergent specifically formulated for the washing of hair and packaged in a user-convenient form. Typically, a shampoo must clean well, rinse easily, impart gloss to the hair, minimize tangle and not damage the hair structure, or the scalp or the eyes.