Citric acid is a remarkable ingredient in soap making. When added to the lye solution at the beginning of the soap making process, citric acid activates a chemical reaction that converts it into sodium citrate.
Acting as a chelator, sodium citrate provides many benefi ts to your soap, such as heightened emulsifi cation, better texture and consistency, and decreased soap fi lm residue. Sodium citrate can enhance the moisturising properties of your soap as well as make it a gentler product for the skin.
Benefits of sodium citrate:
Heightened Emulsification
Sodium citrate encourages greater emulsifi cation in your formula, prompting a more even and stable mixture allowing for a balanced distribution of the ingredients.
Antioxidant Properties
Working as a chelating agent, sodium citrate helps to bind and neutralize metal ions that can induce the oxidation of fats in soap. This oxidation process can lead to rancidity, which spoils the soap and reduces its shelf life. By reducing oxidation, citric acid contributes to the longevity and stability of soap, ensuring it remains eff ective for use over time.
Water Softening
One of the primary functions of sodium citrate in soapmaking is water softening. When soap is used with hard water, it tends to form soap scum, a residue that reduces the soap's eff ectiveness and can leave an unpleasant fi lm on the skin and surfaces. Sodium citrate helps to bind the metal ions found in hard water, such as calcium and magnesium, thereby averting the formation of soap scum. This results in a cleaner rinse and a more eff ective cleansing experience.
Enhanced Lather and Feel
In addition to its chemical benefi ts, sodium citrate can enhance the physical properties of your soap. It's able to improve the soap's lathering ability, making it produce richer and more abundant bubbles. This not only improves the user experience but also enhances the soap's cleansing power. Additionally, sodium citrate can contribute to a smoother and more luxurious feel on the skin, making the soap more pleasant to use.
Preservation
The inclusion of sodium citrate in your soap means it's capable of lengthening the soap's shelf life and aids in the prevention of soap scum or soap ash forming on the surface, therefore assuring your creations stay visually appealing and long lasting.
Calculating the amount of citric acid needed in your recipe:
Calculating your soap recipes carefully is crucial. Citric acid consumes a percentage of the sodium hydroxide or potassium hydroxide; therefore, an appropriate adjustment in your recipe is necessary.
Implementing large amounts of citric acid is inadvisable, as this can result in small white crystals forming on the surface of your soap and may hinder the soap's
effectiveness.
The amount of citric acid required varies depending on if you are making bar soap with sodium hydroxide, or liquid soap with potassium hydroxide. These example calculations are made based on 2% citric acid for bar soap and 1% citric acid for liquid soap. Calculations are all made by weight of the total amount of main soaping oils (not including fragrance or essential oils) . Below calculations are based on 1000g of oil in the batch.
Calculation for sodium hydroxide soap (bar soap) using 2% citric acid
1000g x 2% (1000 x 0.02 in a calculator) = 20g citric acid
So, we'll need 20g of citric acid for our recipe.
- Each 1g of citric acid consumes 0.624g of sodium hydroxide (NaOH)
- We want to use 20g of citric acid (2% of soaping oils) in a bar soap recipe
- The calculation here would be 20g x 0.624 = 12.48g of extra sodium hydroxide needed
- Add the extra sodium hydroxide amount needed to the original amount stated in your recipe. Record the adjusted sodium hydroxide amount in your soap recipe book and note how much citric acid is being used.
Calculation for potassium hydroxide soap (liquid soap) using 1% citric acid
1000g x 1% (1000 x 0.01 in a calculator) = 10g citric acid
So, we'll need 10g of citric acid for our recipe.
- Each 1g of citric acid consumes 0.842g of potassium hydroxide (KOH)
- We want to use 1% citric acid for our liquid soap recipe and we're also using 1000g base oils
- The calculation for citric acid needed is 1000g x 1% (1000 x 0.01 in a calculator) = 10g citric acid
- The calculation for extra potassium hydroxide needed for our liquid soap recipe is 10g x 0.842 = 8.42g
- Add the extra potassium hydroxide amount needed to the original amount stated in your recipe. Record the adjusted potassium hydroxide amount in your soap recipe book and note how much citric acid is being used.
In conclusion, citric acid is a fantastic ingredient in soap making, off ering benefi ts that improve water softening, antioxidant protection, lather enhancement, and preservation. Its multifaceted role ensures that soaps are not only eff ective and long-lasting but also gentle and pleasant to use, making it a valuable addition to any soap-making recipe.