This series is intended to explain the occasionally unclear terminology in 19th century formularies. Drop any corrections in the comments section or my contact form.
There are a number of cosmetic recipes in Victorian formularies that call for premade soaps.
Soap can be used to unify certain oil-water mixtures. A small addition of soap was added to certain hair products to make them easier to wash out. Plain soaps were melted down by perfumers, scented, reformed into tablets or cakes, and individually wrapped in pretty paper—much like melt-and-pour soaps today. These were called toilet soaps, i.e. soaps for the body, not for laundry or dishes.
Most soap recipes in the formularies run “take x pounds of white curd soap/shaving cream and add y ounces of such-and-such perfume”. The most commonly-mentioned soaps in these recipes follow. I used many sources, but this one by Cristiani is pretty comprehensive.
This is a hard soap made with caustic soda and tallow. Some recipes call for a mixture of lard and tallow, which improves the lather a bit. Sometimes vegetable oils are included with the tallow, such as coconut and palm kernel.
Pure tallow curd soap made by the traditional method was good for laundry, but too harsh for human use. This soap was combined by perfumers with oil soap (usually palm kernel) to create toilet soaps that were easier on the skin.
Modern tallow soaps intended for humans have a little more fat added (“superfatting”) to saponify any extraneous lye and make it safe for the body. A women’s magazine from 1898 mentions superfatted soap favorably as a gentle way to keep the complexion clear.
Curd soap remains more popular in Europe than in the States; it seems to have disappeared entirely from American notice in the 20th century. All the recipes I have found (with close resemblance to those from the formularies) come from Germany.
This is a hard soap made with caustic soda and vegetable oils. Sometimes it appears as oil curd soap. It is generically called Castile soap then and now.
In some parts of the world during the 19th century, the difficulty accessing good-quality olive oil led to clever replacements and fillers. Palm oil, sesame oil, coconut oil, linseed oil, and cottonseed oil were all used, among others.
Any kind of hard oil soap bar should work in recipes asking for oil or Castile soap. I use Dr. Bronner’s because it’s the easiest to come by (and local). For extra DIY points, olive oil soap is straightforward to make yourself—this blog post by the Frugal Berry contains instructions and a video for olive-coconut Castile soap.
One book makes an interesting note: pure olive oil soap was possible in the 19th century, but the soapmaker had to use an impure lye from certain plants, such as saltwort. This lye contained both caustic soda and caustic potash. This would keep the bar from being too hard.
This is soap made by caustic potash (potassium hydroxide, KOH) and a portion of caustic soda (sodium hydroxide, NaOH). Pure KOH is used in modern times to make liquid soaps, and pure NaOH is used to make hard bars. The proportion of KOH or NaOH in the recipe, and the season of the year, determines the hardness of a soft soap. The fats in soft soap are typically a mix of animal and vegetable.
Victorian soft soap was used in the creation of scented shaving creams, which have little resemblance to the modern Barbasol-type creams in metal cans. They are simply soft soaps ground with the desired perfumes until a pearly appearance is achieved. When a recipe calls for generic “shaving cream”, they mean soft soap that has been beaten in this fashion. It was ground by machine or by hand with a mortar and pestle.
Further back, in colonial times, “soft soap” was known as a brown jellylike substance. It’s so old-fashioned that most modern recipes also include instructions for building a barrel for leaching lye from wood ashes you have made yourself! Needless to say, I have not tried this. It’s a bit too far back in time to fall under the purview of this blog.