Why would anyone add non-fat dry milk to the laundry? Because the casein in the non-fat dry milk precipitates with the free formaldehyde and then it gets washed out better…
“Formaldehyde present in clothing and sheets can produce allergic reactions. Most frequently, it is an irritant, especially to dry skin and areas exposed to increased friction or perspiration.Casein is an innocuous compound that, when added to formaldehyde, produces insoluble compounds used to make items, such as buttons, billiard balls, and water-proof adhesives. A small handful of nonfat dry milk added to the laundry rinse water precipitates free formaldehyde, this results in reduction of the skin irritation. This process also makes clothing and sheets feel softer. In some fabrics, the formaldehyde continues to be released, and after a few days the rinsing must be repeated.Excessive quantities of harsh laundry detergents may cause the same problem of itching.”
http://archderm.jamanetwork.com/article.aspx?articleid=534309
