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Lavender in Natural Soap
Sep
Lavender… it invokes so many different memories for most people, and I must be honest, I’m not a huge fan of it on it’s own. However, blended with other floral scents, or blends that require a floral undernote, makes it an invaluable scent profile. We use lavender essential oil in various formulations in our handmade soap, liquid soap and shaving soap, as well as body balms etc.
The different botanical types of lavender is a discussion for another time. In this article I want to discuss handmade soap in particular, and how ingredients can affect the aesthetics thereof.
Handmade soap can be very pretty, let’s all face it. As consumers, we mainly buy those as gifts, or as a soap maker, make pretty and intricate decorated soap to challenge our creative side. What can be quite disheartening for some though, is the white ashy film that can form over your soap tops and sides as well.
This white dusting is a deposit of salts and/or minerals, and it is completely harmless. Soap makers call this deposit “soda ash”, and various factors can contribute to it’s formation, with the primary reason using too much water and exposure of raw soap batter to air during saponification.
Certain ingredients may contribute to this efflorescence as well, and I will discuss this in detail further.
We take every precaution to prevent soda ash on our manufactured soap as our production process typically includes using a fairly low amount of water and proper insulation, but infrequently a batch will present with a light dusting of it. Most times it happens quite a while after curing, and then presents in patches over the soap in various spots. Post-processing removes it quite easily, however it can reoccur which can make it difficult to preserve the aesthetics of the soap depending on the design.
I never thought much about soda ash until I read up about linalool and limonene, winter cold air and migration of deposits causing efflorescence.
Lavender essential oil and other oils or fragrances that contain linalool and/or limonene, can develop soda ash. Prolonged exposure to cold air (winter, cold snaps, humidity) will increase the chances of your lavender-scented soap developing soda ash, and can continue to develop soda ash.
Linalool and limonene are terpene compounds found in certain essential oils, as well as fragrance oils, and have a smaller molecular weight than raw soap batter. Dissolved salts in them (from the caustic soda solution, sodium lactate or added salts), or minerals (found in clay or carbon burning process of activated charcoal etc) can migrate outwards to the surface of the soap.
Cold ambient temperatures can aid with this transport (possible contraction) as can humidity (condensation and evaporation of water) from the surface.
In short, as soap makers, it is common knowledge that soap made with high water can cause soda ash, as can improper insulation. Pairing your soap with lavender essential oil, or oils that contain linalool and/or limonene, can increase your chances of soda ash developing over time.
Formulating with activated charcoal, clays, additional salts etc, will increase it even more, as will storing them outside of a temperature- and humidity-controlled area.
So, when your lovely batch of floral scented soap develops a white film over time that washes off easily, thank the linalool content, and the same goes for limonene in certain citrus scent blends.
Soda ash however, is not to be confused with fatty bloom, which I have discussed in detail in this article.
For everyone else who aren’t making soap, the white dusting on your recently purchased natural soap is completely harmless, and is a natural deposit of salts. It can be safely wiped off, or rinsed off prior to use.