What kinds of test soils are used in detergent testing?
Synthetic soils are often applied to coupons to use in testing detergents. Typically a soil will be made from some kind of binding natural oil such as vegetable oil or vegetable shortening combined with a protein such as whey powder or egg powder. Additionally there may be motor oil or used motor oil; vacuum cleaner bag dust; carbon black; and clay soils. Sometimes these mixtures would have synthetic hard water such as 150 ppm hardness (2/1:Ca+2/Mg+2) mixed in. In general you want your synthetic soil to mimic the type of residue that you are trying to develop a detergent or cleaning process to clean.