How to Tell Natural Soap from Synthetic Soap

Put simply, any cleansing product made through saponification is called soap, and everything else is called syndet. The lathering agents from soapberry and bo ket (Gleditsia), however, are called natural cleansers. So here we have the groups: natural cleansers, soap, and synthetic detergents. And at heart, all 3 groups are cleansers.

Ginger Ale Soap

Syndet is the kind of cleanser we are probably most familiar with in everyday life today. It is found in almost every cleaning product, from body care to household cleaners, usually from the sulfate family, and derived from processed fats or petroleum products. Familiar names include:

Petroleum-derived lathering agents: Sodium Lauryl Sulfate (SLS), Sodium Laureth Sulfate (SLES), and so on. These are strong detergents and quite controversial. We find them in almost all industrial cleaning products because they are cheap and clean effectively. Because they clean so strongly, they strip away the skin's protective acid mantle, which leads to skin irritation. On top of that, after stripping, moisturisers such as glycerin, B5 actives, vitamin E and so on are added back. Gradually our body forgets its own self-balancing mechanism because it becomes dependent on them, which leads to poor skin health and skin conditions such as dermatitis, folliculitis, psoriasis and more.
Lathering agents derived from processed plant oils: Sodium Cocoyl Isethionate (SCI), decyl glucoside, coco glucoside, cocamidopropyl betaine (CAPB), sodium methyl cocoyl taurate (SMCT), Sodium Coco Sulfate (SCS), Lauryl Glucoside, and so on. These lathering agents are safer and gentler than the group above, but I still class them as synthetic detergents because they still go through a processing step. Occasionally I do use these cleansers in a few products, because they suit most people when making shampoo: they are convenient and give a pleasant feel after washing, and not everyone has the patience to use something completely natural and wait a while for their body to get used to it.

Soap: I class it as a natural cleanser. To make it from plant fats, or animal fats (lard, tallow and so on), saponification has to take place to produce a natural cleanser. The maker calculates the recipe so that once the reaction is complete, no base remains, and decides what skin type it is meant for. That is why, even though they are all handcrafted soaps, each Beo Tam soap gives a different lather and a different feel on the skin. Why some soaps are hard and some soft, some have lots of big bubbles and some a fine lather, and so on. In this group, the common products we usually see are bar soap and liquid soap (Beo Tam's essential oil Castile liquid soaps are made on a liquid soap base). For natural cleansers from bo ket and soapberry, what produces the lather and does the cleaning is saponin, which cleans surfaces when dissolved in water. This group works in a similar way to soap.

Beo Tam natural handcrafted soap

How to tell whether a product is made from natural cleansers or soap, or from synthetic detergents:

Read the ingredient list: if the ingredient list has a list of plant oils or animal fats along with lye, NaOH or KOH, or English names such as Lye, Sodium Hydroxide, Potassium Hydroxide, or the words "Saponification from + names of plant oils", or names starting with Sodium followed by the root of fatty acids found in plant oils such as lauric, palmitic, stearic, myristic and so on, it is soap; anything else is a synthetic detergent.
Measure the pH: products that combine synthetic detergents have mostly had their pH adjusted to fit the "skin pH concept" (I will write a post about pH so everyone can understand it properly), around 5 - 6.5. Soap, on the other hand, always has a pH >7, and liquid soap alone can reach a pH of 7 (Beo Tam's liquid soap achieves this). Lowering the pH of handcrafted soap to an acidic level is impossible, because by nature it is an alkaline salt, so adding an acid makes it react with the new acid to form another salt, which reduces the soap's cleansing power. If someone promises that their handcrafted bar soap is pH-balanced, either they do not understand the nature of soap or they are deliberately misrepresenting the facts.
How your skin feels after use.

With natural cleansers, after washing you will feel truly clean, with your skin dry and fresh and no film left on it. But after about 5 to 10 minutes your skin will feel soft again, because by then it is rebalancing itself through its natural mechanism. So many people switching from industrial shower gel to soap find this fresh, bare feeling a little strange and are somewhat hesitant if they don't understand how it works.
With synthetic detergents, you will feel as if there is a film on your skin. Many shower gels on the market even leave a slippery feeling on the skin because of the silicone layer left behind to give the illusion of smooth skin. This silicone layer clogs your pores so they cannot breathe, and your skin cannot regulate itself to rebalance its acid mantle, leading to dermatitis, folliculitis and more.

This is knowledge drawn from practice and from my own learning and experimenting, shared with you so that we can properly understand the nature of different cleansing methods and make the right choice for ourselves.