Soda ash – what, why and how?

In this article, I would like to provide you with a more detailed explanation of soda ash on soap. Soda ash is a white layer that can form on the surface of handmade soap and is composed of sodium carbonate, which is generated during the saponification of oils and fats.

What is Soda Ash?

Soda ash is a chemical compound with the formula Na2CO3. It is a white, inorganic powder found in nature in the form of minerals such as a mixture of sodium carbonate and sodium hydrogen carbonate (trona) or sodium bicarbonate (sodium hydrogen carbonate). Soda ash is also commonly referred to as washing soda or soda.

How Does Soda Ash Form on Soap?

Soda ash is produced during the saponification of oils and fats using a lye solution, which can be either sodium hydroxide or potassium hydroxide. During saponification, the fatty acids in the oils and fats react with the lye to create salts of fatty acids, which constitute the actual soap.

In addition to soap, the saponification process also yields sodium carbonate. Sodium carbonate is a byproduct of saponification, formed when the lye solution within the soap mixture reacts with carbon dioxide. Carbon dioxide is a gas present in the air and may also originate from the water used in the soap-making process.

Additional Insights:

  • Effect on Fragrance:
    In some cases, soda ash formation might trap fragrance oils, affecting the scent of the soap. Soap makers may need to consider this when formulating their recipes and choosing curing methods.
  • Humidity Impact:
    Humidity levels in the curing environment can influence soda ash formation. Higher humidity can accelerate the formation of soda ash, while lower humidity may slow it down. Soap makers may need to adjust their curing conditions accordingly.
  • Alternative Prevention Methods:
    Besides the methods mentioned, some soap makers also use techniques like spraying the soap surface with rubbing alcohol after pouring it into molds. This can create a barrier that helps prevent soda ash formation.
  • Long-Term Storage:
    Even if soda ash forms initially, it may sometimes dissipate over time during the curing process or with proper storage. Soap makers often recommend allowing the soap to cure for several weeks to months for optimal quality, during which soda ash may naturally diminish.

How Can Soda Ash on Soap Be Prevented?

Soda ash can be prevented through several measures:

  • Carefully cover the soap mixture:
    Always securely cover the soap mixture with plastic wrap or a cloth to prevent it from coming into contact with carbon dioxide.
  • Allow the soap to fully cure
    Do not unmold the soap too early: before removing it from the mold, typically around 24 hours.
  • Use distilled water:
    Distilled water does not contain carbon dioxide. Using distilled water can reduce the formation of soda ash.
  • Use distilled water:
    Distilled water does not contain carbon dioxide. Using distilled water can reduce the formation of soda ash.

How Can Soda Ash on Soap Be Removed?

Soda ash can be removed from soap using a steamer or a damp cloth.

Steamer: Place the soap in a steamer and steam it for a few minutes. This will dissolve the soda ash, making it possible to wipe it away with a soft cloth.

Damp Cloth: Rub the soap with a damp cloth to dissolve the soda ash, then wipe it away with a soft cloth.

Conclusion

Professor Blue

Soda ash is not harmful to the skin but can affect the appearance of the soap.

To avoid soda ash formation, follow the above-mentioned tips.