Prosanis is not a line of clothing, but neither is it a union label. It was a label that indicated the garment was manufactured under safe and healthy working conditions. In other words, this particular manufacturer allowed a board – the Joint Board Sanitary Control New York City – to inspect their facility and thus they were allowed the use of the label. It was only used from 1924-1929, so it provides a very good dateline for an item. It never quite caught on and stopped being used in 1929.
Written by old and beautiful vintage
See also Union Labels.