The effect of electrolytes on soil redeposition in laboratory and laundry practice

Conclusions 1. Fatty acid soaps and pure synthetic detergents have a far greater suspending power for Aquadag soil than either of these types when used in the presence of inorganic salts. 2. Any inorganic salts of the type of sodium chloride, sodium sulfate, calcium, or magnesium salts, the common alkali or phosphate builders, all tend to cause deposition when used alone or with surface‐active materials. 3. Fatty acid soaps are self‐protecting against hard water salt effects. 4. Synthetic detergents require protection against calcium and magnesium salts, which can be achieved by adding calcium ion suppressants. The effect of neutral salts, such as sodium chloride and sodium sulfate, can be eliminated by omitting them from the composition. When these salts are present in minor amounts, the use of protective colloids, such as carboxymethyl cellulose, affords some protection.