Dear reader,
Now is the time for a simple technical explanation on the creation of soap, seen by the amateur chemist, or the handyman
Soap: a fairly simple chemical reaction after all
In short :
Fat + soda => soap + glycerol
There, all is said ! Just need to develop !
Because yes, it is enough to emulsify oil in a solution of caustic soda to obtain after "a certain time", good soap and glycerine (or glycerol), intimately mixed. It's as simple as making mayonnaise ..., almost as simple. (But mayonnaise is for another blog ...)
Some words matter :
« It is enough » : Indeed, we get a very good soap (natural, cleanser, excellent for the skin, ...) with just three ingredients: fat, water and a caustic substance.
« Emulsify » : oil and water do not mix, everyone knows that. In order for the saponification chemical reaction between the oil and the caustic solution to occur, the oil must be dispersed in the form of tiny little droplets in the aqueous sodium hydroxide solution. A good shot of a “dipping mixer”, like for mayonnaise.
« Caustic soda » : dissolve caustic soda (NaOH, for a solid soap) or potassium hydroxide (KOH, for a liquid soap) in water.
« A certain time » : « Who feeds the Loch Ness monster ? » In this case, most of the saponification reaction takes 48 hours, but the process will be completely over after ... about a month! And ban on trying a soap before this time, it could still be slightly caustic.
« Intimately mixed » : the “sap” cold saponification process produces soap with a certain amount of glycerin, around 7% of the mass of the finished product depending on the oils used. This glycerin causes the soap to leave a protective film on the skin and not leave it dry. Glycerin is a hydrating, solvent and lubricating agent.
Soap is not just simply mayonnaise !!!
Here I must nip the enthusiastic momentum of apprentice soap makers in the bud: Do not rush into your kitchen a can of olive oil and a bottle of liquid drain cleaner under the arm with the intention to offer a wonderful handmade soap to your loved ones.
Indeed, making cold soap is a potentially (very) dangerous chemical process. Caustic soda is really very ... caustic; chemical reactions are exothermic (produce heat) and the manufacturing procedure requires compliance with (very) strict safety rules.
We can therefore use a bar of soap safely while being naked, while making said bar requires glasses, protective clothing and gloves, and caution !
Let's pause on these wise words before coming back to more concrete indications in a next episode.
See you soon !
Bruno, Artisan Soap Maker