Grasse, SE France, the capital of perfumes. In the ASFO facilities, a training centre for skills in perfume, aroma and cosmetics industries. Carole André is the trainer for the full morning, giving a lab course about the manufacturing of soap. Theory, recipe, putting into practice … some foiled results and some beautiful bath soaps come after this 4-hour practical training that CosmeticOBS-L’Observatoire des Cosmétiques attended.
They arrive, one by one, clothed in white lab coats, then sit around a large table and open their notebooks like schoolchildren. Yet these ten students (mostly women) have left their schooldays behind them. In professional retraining or work placement programmes, they are undergoing training here to become ‘manufacturing operators’: ‘ Here we train the future employees of fragrance, flavour, and cosmetics companies, ’ explains Isabel Torrente, the ASFO training assistant. ‘ These are the people who, in the manufacturing and production workshops or laboratories, will execute the recipe devised by a formulator. After they are trained, they will be given a qualification certificate that allows them to work in all kinds of businesses, all over France. Demand for qualified personnel is very high in the industry .’
So here they all are today, gathered around Carole André. As a perfumer and formulator, and also a
CosmeticOBS-L’Observatoire des Cosmétique expert
, she gives her training courses here regularly, in addition to her consulting activities.
On the agenda for today: soap making.
Once everyone is settled, the class begins.
To get everyone started on equal footing, Françoise is asked to write down the basics of saponification on the board. She explains that saponification is the chemical reaction of a strong base (lye or potash) with an oil, of either vegetable or animal origin. Potash is used to make liquid soap, whilst lye is preferred for solid bars of soap.
This is the equation: base + oil = soap + glycerine + unsaponifiables. Soap can be cold-processed, but heat speeds up the reaction. This reaction depends on the oil chosen; each one has a different ‘setting’ temperature and cooking time. For example, olive oil must be heated to about 105°C, whilst 95°C is enough for coconut oil and 80 to 85°C is the right range for grapeseed oil…
Each oil also has its own saponification value (SAP value). It is important to be aware that each oil comprises a saponifiable portion (which can be transformed into soap) and an unsaponifiable portion (which will be considered a residue after the reaction). The SAP value is the amount (in mg) of potash required to saponify 1 g of fat. If lye, which is more potent, is used as the base, the result must be multiplied by 0.7.
The SAP value indicates the capacity of oil to be transformed into soap. The higher this value, the more saponifiable the oil. The value for palm or coconut oil is 254 mg, while that of olive oil is only 192. It is easy to see that the first two oils are more profitable (and they produce perfectly white soaps as well), which is why they are frequently found in store-bought products… but the soaps obtained with these oils are harsher on the skin than those made with olive oil, which is gentler (and more expensive).
To make soap gentler, it can be ‘superfatted’ by reducing the amount of base required for saponification (by about 5%). Since the oil is not completely saponified, some of it remains in the finished soap.
Soap in practice
Once the students have absorbed this knowledge, all that remains is to apply it in the real world. Two teams have already begun heating their mixtures at the workbench. But very quickly, the appearance of one of them seems a little off. The trainer, summoned to the rescue, identifies the problem right away. The base hadn’t been prepared properly: the process was a bit hurried, and the soap is ruined from the start! ‘ Soap seems simple enough to make ,’ says Carole André. ‘ But if you don’t follow the recipe exactly, you’ll end up having to start all over! ’
So the team starts over again. They weigh the ingredients, mix them in the beaker, set up the agitator (to further accelerate the reaction), and apply slow heat, taking care to cover the mixture to avoid wasting energy.
And when it starts to thicken, you have to watch the preparation as closely as you would milk that’s about to boil over
,’ Carole reminds everyone. Because it can boil over, just like milk.
So you have to keep a careful watch, sometimes for over an hour before anything actually starts to happen. Finally, the mixture starts to get cloudy and thicken bit by bit. At the end of the process, the preparer must continue to stir the mixture, but by hand, using a spatula. All the way until the soap is done cooking.
Of course, in an industrial laboratory, all these operations are programmed and timed, and are carried out in large vats with almost no human intervention. But here we are learning to carry out every step.
Once the soap is cooked, it must be purified to eliminate the strong base residues, resulting in a gentler pH. The operation is carried out with salted water (350 g of salt per litre of water). ‘ Why do we use salt-saturated water? ’ asks Carole. Because soap dissolves in pure water, but not in saltwater. ‘ Exactly, ’ she confirms. ‘ That’s why you can’t wash with soap in seawater, and it’s why sailors use syndets (soap-free cleansers) .’
The next step is filtering, which removes the saltwater. The artisanal method for doing this is to draw off the water gradually, but in the laboratory vacuuming is used.
And now for the result: soap flakes!
But how do you get a bar of soap?
The process isn’t yet complete. The flakes must be blended, at which point additives like fragrance or colourings are added. Citric acid can also be added to lower the pH, as can calcium chelators. Next, the soap will be compressed in moulds and dried before it takes the form of soap bars as we know them.