The key to properly inspecting shampoo is to know its ingredients and be able to test for these ingredients in a lab.
Key Raw Ingredients in Shampoo
Deionized Water
The first main ingredient in shampoo is water. 70-80% of the shampoo formula is made up of water. A special kind of water is used in shampoos, which is called deionized water.
Detergent / Surfactants
The second main ingredient in shampoo is detergent. Detergents, are also known as surfactants, are the cleansing ingredient in shampoo's. Surfactants are surface active which means they interact with a surface which in this case is hair. Some common detergents that are used in shampoos are sodium lauryl ether sulfate, ammonium lauryl sulfate and sodium lauryl sulfate.
Conditioners
Conditioners are added to shampoos to counteract the damaging effect of surfactants on hair and fabrics. Conditioners include guar hydroxypropyltrimonium chloride, dimethicone, and quatemium 80. These conditioning agents deposit onto the surface of the hair and enhance the softness of the hair and root system. Shampoos that feature conditioning agents are generally titled a 2-1 shampoo and conditioner.
Foam Enhancer
Several different types of surfactants are added to shampoos to enhance the cleansing and foaming characteristics of the shampoo formulation. A foaming surfactant is called alkanolamide. This ingredient will help increase the bubble size and density of the foam.
Thickness Enhancer
Alkanolamides that create the foam of the shampoo also make shampoo thicker. Other ingredients are also used to assist in increasing the thickness of shampoo. These ingredients are listed in the International Nomenclature of Cosmetic Ingredients as methylcellulose, and sodium chloride.
Preservatives
Since shampoos are made from deionized water, contamination from bacteria and molds are possible. Preservatives are added to shampoo to prevent future and current bacterial growth. Two preservatives that are used in shampoos are methylparaben and DMDM hydantoin.
There are 3,734 cosmetic manufacturers in China. Ensure when you're choosing your shampoo manufacturer, or the raw materials manufacturer, that you have all the proper shampoo inspection and quality control tests performed by a quality control specialist.