There are two main categories of solid shampoo on the market and we need to know how to distinguish them to buy what best suits our needs or lifestyle:
First, note that it is impossible with a soap to obtain a neutral or acidic pH, a soap is alkaline. That being said, our scalp is acidic, with a pH around 5.5.
Syndet (the bars with noodles inside)
These are the shampoo bars that most closely resemble your good old bottle of shampoo that you want to get rid of.
They have a pH adapted to the scalp and do not cause the weighing effect of soap in the hair. The ingredients are relatively the same and the effect on the hair is therefore similar.
Syndet is an abbreviation for Synthetic Detergent, which means that your bar of soap is actually a bar of synthetic detergent. It's not necessarily bad, though. I would even say that... What is worse for our hair... These are:
Soaps... which have been renamed shampoo!
These are bars of soap, saponified oils which have a pH much too high for the scalp. Some add noodles and several additives to give a cool look and try to adjust the effect on the hair but be careful; Too high a pH can damage your hair and even wash out your beautiful coloring.
The merchants will also suggest rinsing your hair with apple cider vinegar, to lower the pH further. This is a question of preferences, as long as the consumer is informed of what he is using... But this is unfortunately rarely the case.
Personally I don't like the effect of soap in my hair and even less the smell of vinegar when rinsing but that doesn't take away from the fact that there are very good shampoo-soaps on the market and that some people adopted them. A treatment is necessary to remove the silicones deposited on your hair following washing with pharmacy shampoo, this can last around a month so don't judge too quickly and see for yourself what you prefer.
If you are not sure when shopping for a solid shampoo, send me your list of ingredients and I will help you understand the composition of your little find.
Some detergents are more harmful than others, so here is the important information to know if you want to get a syndet:
The noodles are made from:
SCI
My favorite, it is gentler and has a very low sulfate concentration.
INCI Name: Sodium Cocoyl Isethionate It is also known as sodium isethionate. It is a sodium salt derived from coconut oil. ... Basically, sodium isethionate helps water stick to the dirt and oil on your skin, allowing it to be removed. Due to the mild nature of sodium isethionate, it is often found in baby toothpastes and soaps.
or...
SCS
To be avoided, in my opinion. (see also SLS)
INCI Name: Sodium Coco Sulfate,
Some people use it and have to lower the pH, which is very difficult given that it drops drastically to a certain point. I suggest you ask the merchant for a pH test before purchasing a product that contains it and make sure the ingredient list contains a citric acid or other acid that can lower the pH.
The process for making sodium coco sulfate is the same as for sodium lauryl sulfate (which I'll discuss below). Although the proportion of lauryl sulfate in sodium coco sulfate is not strictly defined, this percentage could be higher and manufacturers are free to make it as high as they wish. In summary: sodium sulfate contains mainly SLS.
SLS
Which I also avoid...
INCI Name: Sodium lauryl sulfate or Sodium lauryl sulfate is a synthetic detergent used in a wide range of personal care products. Unfortunately, many so-called “natural” products contain SLS.
SLS belongs to a class of medium to strong surfactants (or “surfactants”) known as alkyl sulfates. As a group, these chemicals have a commercial advantage: strong cleaning power, high foam production (which people associate with better cleaning - although foaming and cleaning are two very different things), and a cost of very low production. Unfortunately, they are also irritating to the skin, in part because they strip the skin's protective oils. In fact, sodium lauryl sulfate is a gold standard for producing irritation in skin irritation studies.
SLES
Which I also avoid
INCI name: Sodium laureth sulfate. Similar to SLS, a little softer.
SLSA
Is very popular, they are everywhere. I use it to improve the foaming effect.
INCI Name: Sodium Lauryl Sulfoacetate
It has a very similar name to one of the most common sulfated ingredients, sodium lauryl sulfate (SLS). So you might be tempted to avoid it. Both ingredients are surfactants that can create bubbles and make cleansers lather, but that's where the similarity ends. According to Syd Salmon of SLI Beauty, SLS is a cheaper lab-made ingredient, while SLSA is naturally derived from coconut and palm oils. Like laureth disodosulfonuccinate, the SLSA molecule is too large to penetrate the skin, causing less irritation than sulfates.
Coco Betaine (CAPB)
Very mild surfactant, I even use it in a toothpaste recipe.
INCI name: Cocamidopropyl betaine
It is a mild atmospheric surfactant that is derived from coco-methyl esters. It is valued for its foaming qualities and its ability to serve as a thickening and viscosity agent.
Cocamidopropyl Betaine leaves hair and skin soft and smooth and is compatible with other cationic, anionic and non-ionic surfactants, making it a favorite for cosmetic formulators. It is not suitable to be the sole surfactant in a formulation, but can act as a primary or secondary surfactant.
Links:
La Bulle's recipes here
To see how solid shampoos are made here