A Brief Introduction Into the History of Soap Production
The earliest recorded evidence of the production of soap-like materials dates back to around 2800 BC in ancient Babylon. A formula for soap consisting of water, alkali, and cassia oil was written on a Babylonian clay tablet around 2200 BC. The Ebbers papyrus indicates the ancient Egyptians bathed regularly and combined animal and vegetable oils with alkaline salts to create a soap-like substance. Egyptian documents mention a soap-like substance was used in the preparation of wool for weaving. In the reign of Nab nidus (556–539 BC), a recipe for soap consisted of uhulu (ashes), cypress (oil) and sesame (seed oil) 'for washing the stones for the servant girls'.
Soap has a long and fascinating history, and certainly, in Europe the Celts were known to use a substance made from animal fats and plant ashes for bathing and washing. The Romans originally used soap made from goat tallow and wood ashes and there is evidence of an entire soap factory under the ruins of Pompeii, complete with finished bars. Soap has been made in Europe since the 13th century, and the countries with access to olive oil were able to produce superior soap for personal bathing. Northern France and England only had access to animal tallow and this produced an inferior bar, mainly used for laundry and textile cleaning.
In the 16th century, three broad varieties of soap were available: coarse soap made from train oil (extracted from whale blubber), sweet soap from olive oil and speckled soap from tallow. For a while, the making of speckled soap was forbidden, not simply because it smelt so bad but because its manufacture would deplete the nation’s tallow reserves, thereby driving up the cost of candles beyond the reach of the poor. As a result, soap was heavily taxed and became a luxury item only readily available to the rich. Eventually, market forces virtually eliminated sweet and speckled soaps, despite the difficulty of making an odorless coarse soap. Understandably, it was not long before perfumed soaps were introduced from Italy.
Throughout the 19th century the chemistry of soap-making became better understood with the discovery of the different fatty acids present in neutral fats and oils and this, in turn, led to the establishment of the fundamentals of the modern-day process involving the saponification of neutral fats or fatty acids with the appropriate caustic material. Caustic soda will produce a harder sodium soap whilst caustic potash will yield the softer potassium soaps. The selection of specific fats and oils will yield a liquid soap.
Overall, although production methods and techniques may have changed drastically from those earliest days it is worth remembering that, the basic chemistry of soap remains virtually unchanged.