Zoom on glycerin


Wikipedia, YouTube, and Google aren’t the only tools to get to understand a topic in depth. Over the years and through experience, we have gained knowledge we are proud to share with you.

It’s easy! For each question, we come up with an answer!


In a soap, where does glycerin come from?

Glycerin appears when soap is made. A soap is made through a process called saponification which consists of the reaction between an alkaline agent (for example caustic soda, potash, ashes, etc.) and a fatty substance (vegetable oil – coco, olive, etc. – or another fatty material such as animal fat).

Saponification can operate in two ways. It can either be hot or cold.

Hot saponification consists of heating the ingredients (oil and soda for example) for a few hours at high temperature. This accelerates the saponification process as the drying time (or the cure) can be reduced to only one day.

Cold saponification is done at room temperature. The mixture must then be left to dry for about a month.

Following this saponification (hot or cold), a cleansing base - also called “soap” - is formed at the same time as glycerin.


But what exactly is glycerin?  

Glycerin is an essential component in all fatty substances and is obtained at the same time as soap during the saponification process. It is therefore naturally present in all soaps.

Glycerin can then be:

  • removed: in Marseille soap for example, glycerin is removed when the soap mixture is washed.
  • left as it is: our soap for example has natural glycerin derived from its olive oil.
  • added: other soaps sometimes add glycerin of vegetable or animal origin, or worse, derived from petroleum or synthetics.

To find out if your soap contains glycerin, it will appear in the INCI ingredient list (International Nomenclature of Cosmetic Ingredients) under the name of - Glycerin or Glycerol

 However, it is difficult to determine the origin of glycerin as they all appear under the same INCI name. This name is the same for vegetable glycerin (palm oil, olive oil), for synthetic glycerin (derived from petroleum), or for glycerin from animal fat! This is why glycerin may appear (wrongly) in some cosmetic scanning apps as an ingredient which is possibly derived from palm oil.


Can glycerin impact my body?

The fact that glycerin is left, removed, or added in soaps will necessarily have a direct impact on your skin.

When soaps are made through hot saponification, like the "Savon de Marseille" for example, the mixture obtained is then rinsed with salty water. This removes the remaining soda in the mixture, which is harmful for the skin. However, by doing this, glycerin is also removed even though it is beneficial for our skin. This is why soaps made through hot saponification have a more exfoliating feeling, not ideal for people with sensitive, irritated, or fragile skin.

The mixture obtain through cold saponification isn’t heated. The oil’s benefits and properties are therefore kept as the ingredients stay more or less at room temperature (below 60°C). 

Natural glycerin has moisturising and beneficial virtues for our skin. In our soap, we decided to keep the glycerin for its properties. As well as its benefits, our soap is 7% superfatted thanks to a surplus of non-saponified oil. This allows our soap to thoroughly nourish the skin, to protect it by leaving a thin layer on the skin, and to be suitable for everyone, even those with the most sensitive skins.


Isn’t glycerin bad for my pipework?

Many DIY cleaning recipes recommend using soap without glycerin as it can clog pipes or bath/shower drains. However, these recommendations mainly apply to glycerin which has been added and is present in high quantities.

So it is still possible to use our soap, our soap flakes, or any other soap with natural glycerin to make your own laundry detergent and other household products. You simply need to launch a wash cycle with soda crystals (two tablespoons) and to set it at a high temperature (60°C minimum). Do this around once a month with your washing machine.

If you notice soap residues in your bath or shower drains, you can also pour soda crystals down them.


Can glycerin damage my clothes?

If you do use a homemade laundry made with a soap containing glycerin, natural of course, it will in no way impact your clothes, on the contrary.

Glycerin has softening properties, just like on your skin, and can soften and protect your clothes (in particular wool clothes). It also helps thoroughly wash your clothes as it can dissolve stains and can also be used to stretch shrunken clothes.

If certain laundry detergents are likely to cause you allergic reactions, you can make your own laundry liquid with a soap containing natural vegetable glycerin. In fact, we often receive positive feedback from our community for whom our laundry liquid recipe with our soap flakes is (nearly) a miracle!

For some clothes, it isn’t recommended to use glycerin, for example period panties or reusable nappies. It is still possible to use a soap with glycerin to make your own laundry liquid if you do a regular declogging of your nappies, period panties, and machine.


Can my soap choice impact the environment?

Of course. The way a soap is made as well as the ingredients used may have an ecological impact. At a consumer level, you must be aware of a few facts before buying a soap.

First of all, it is best to go for a soap bar as it generates far less waste and its impact on the planet is therefore weaker. It needs less or no packaging at all. As an example, our soap is wrapped in a brown paper entirely biodegradable and can also be bought in bulk in our shop and with some distributers. No more containers = less plastic! 

Secondly, the way a soap is made is not without significance. Hot saponification requires a great deal of energy to heat the ingredients as well as a huge amount of water to wash the soap and remove the excess soda. Remember, this is also when glycerin is removed. Cold saponification, however, is a slow process requiring little energy. No need to wash the soap as soda is no longer present. This saves a significant amount of energy and water which won’t be discharged into nature.

As well as the initial production, the type of oil chosen for the soap’s fatty substance plays an important role. All non-sustainable oils need to be avoided. Let’s take palm oil as example. The oil itself isn’t bad for the skin, however it significantly contributes to deforestation. Palm oil appears as sodium palmate or sodium palm kernelate in the INCI list. The oil chosen can also have an ethical cost as some soaps add animal fat - sodium tallowate in the INCI list.

To get back to glycerin, if it has been added to the soap, it can either be synthetic or derived from petroleum-based products. Its impact is significant, and we are saying this once again: it is best to go for soaps (and this is valid for all products) containing natural glycerin of vegetable (and sustainable) origin.

Unfortunately, as mentioned before, the INCI list alone isn’t enough to know if the glycerin in a soap is of synthetic, animal, or vegetable origin. It’s up to the consumer to determine this, do some research, and even question the manufacturer if they aren’t transparent on this.


So, should we choose a soap with or without glycerin?   

We think that it’s best to go for a soap which has glycerin, and more specifically glycerin from vegetable oils. However, you need to be careful which oils are used, as they aren’t all equal in terms of ecological impact (and effects on the skin).

Soaps made through cold saponification are much better in terms of environmental protection because of the way they are made. So, the twin goals are: glycerin and cold saponification.

We recommend that you choose quality soap bars made through cold saponification containing natural and sustainable glycerin which respects your skin and preserves the environment.