Journal of the Nelson and Marlborough Historical Societies, Volume 2, Issue 4, 1990
No doubt there were many different brands of soap available, but the two that I best remember were Lifebuoy and Sunlight. Soap was also sold in long bars. I remember that my Mother always used St Mungo powder for her copper washing.
From time to time, a supply of home made soap was boiled up in the copper. Freshly rendered down tallow was readily available on the farms, where mutton was butchered on the premises. This tallow became the main ingredient, but folk had recipes to tell them what other ingredients to use to produce a satisfactory product. I haven't a recipe to refer to, and the only ingredients which I remember were borax and caustic soda, obtained from the store. After boiling, the mixture was cut up into bars and squares, while still warm. When kept, it became very hard and was not suitable for personal washing, but was ideal for scrubbing and various other purposes.