Using an acidic "sour" rinse for laundry does not remove all detergent residues per se. Sour rinses were used in commercial laundries to counteract the highly alkaline nature of the detergents often used to "break" soils in the days before modern enzymes and surfactants. Sour rinsing was also used in the days when soap was the main detergent for cleaning laundry as well.
Both of the above counted on weak acids to perform several functions:
Bring down the pH of textiles washed to a level which would not cause skin discomfort when said textiles came into contact with skin.
Help remove mineral residue such as calicum and soap scum (which is mainly mineral residues combined with the fats, oils and other ingredients found in soap). This helped laundry look "whiter" in the same way using vinegar to clean away soap scum from a bathtub.
All these methods relied upon one using either an alkaline detergent an or soap for laundering. Most laundry detergents today are neutral to near neutral and in some cases mildly acidic, therefor acid rinses aren't going to remove much. Liquid detergents in general do not use sodium carbonate, nor other highly alkaline substances, and are near neutral. Thus their residue is more surfactant based, and rinsing with all the vinegar in the world is not going to remove said residue.
L.
Both of the above counted on weak acids to perform several functions:
Bring down the pH of textiles washed to a level which would not cause skin discomfort when said textiles came into contact with skin.
Help remove mineral residue such as calicum and soap scum (which is mainly mineral residues combined with the fats, oils and other ingredients found in soap). This helped laundry look "whiter" in the same way using vinegar to clean away soap scum from a bathtub.
All these methods relied upon one using either an alkaline detergent an or soap for laundering. Most laundry detergents today are neutral to near neutral and in some cases mildly acidic, therefor acid rinses aren't going to remove much. Liquid detergents in general do not use sodium carbonate, nor other highly alkaline substances, and are near neutral. Thus their residue is more surfactant based, and rinsing with all the vinegar in the world is not going to remove said residue.
L.