Soap making isn't rocket science, but it is chemistry. You have to understand the interactions between ingredients. You have to know how much oil to formulate or how certain natural ingredients will change colour in that solution. Each soap begins with a very specific formula that is carefully calculated to include sodium hydroxide. If the formula requires .032oz of a certain oil, that doesn't mean .05 or .02 - it has to be exact.
Speaking of sodium hydroxide (lye), it is impossible to make soap without it. All true bars of soap are made with sodium hydroxide (potassium hydroxide is used for liquid soap). If your bar doesn't have this ingredient, then it's basically detergent. How can you tell? Look for any oils like sodium cocoate, sodium olivate or the word saponification. This means the oils have been mixed with lye to create the soap.
The cold process way of making soap involves using very cold distilled water in exact amounts and carefully adding the sodium hydroxide to that cold distilled water in exact amounts. NEVER the other way around. If you were to add water to sodium hydroxide.....kaboom.
Sodium hydroxide is caustic. It doesn't play well with metals like aluminum (it creates hydrogen gas) and it's dangerous to breathe the fumes. It can burn your skin. When making lye solutions, soapers wear a mask, protective eye gear, gloves, long sleeves, pants, shoes and make sure the ventilation is on. You'll notice a more serious looking mask in the picture below. I sometimes use this one if I'm making many batches in one day, otherwise a basic mask is fine.
Once the lye is stirred gently, an exothermic reaction occurs and the cold water instantly becomes very hot. It changes from a cloudy to clear solution and also becomes cooler after 15-30 minutes. Once a certain temperature is reached, it can be carefully mixed with the oil solution mixture, along with colours and scents if desired.
As the lye water is mixed with the mixture of oils, this is when saponification begins. Without getting too technical, saponification is the chemical reaction between the lye water and the fatty acids of the oils. This process usually takes 24-48 hours and during that time, it's best not to manipulate the loaf of soap with bare hands. After that time, it is safe as the loaf hardens and is cut into slices. The slices are then left on a custom shelf (with proper temp and humidity) to cure and the sodium hydroxide is transformed.
The curing process takes about 4-6 weeks during which time the ingredients settle and the bar becomes closer to a pH level of 8-9 for safe use.
At that point the lye is no more .... it becomes soap.
Actually the real magic is developing the right combination of scents and colours to make designs. This step is tricky and if a mistake is made, the loaf is lost. Rebatching the soap isn't ideal and usually fails. Ingredients can be expensive, so mistakes are carefully avoided!
And so while soap making is chemistry, it's also design and creativity.
There are endless possibilities. More importantly, the knowledge of exactly what goes into these bars of soap is gratifying. So the next time you pick up a bar of soap, you'll know the process it took to make it at a basic level, but also read the label for the ingredients list and make sure you're getting soap and not detergent.
