Soap Bar Formulation - Adding Additives

Hello,

Regarding your soap bar formula and the addition of EDTA 2Na, BHT, and BHA, here's how you can incorporate them and information about your previous experience with EDTA 4Na.

Purpose of these additives:

• EDTA (Ethylenediaminetetraacetic acid): A chelating agent. It binds with metal ions in water and oils, preventing soap scum, improving lather, and helping to prevent rancidity and discoloration caused by metal catalysis.
• BHT (Butylated hydroxytoluene): An antioxidant. It protects oils and fats from oxidation, which causes rancidity (unpleasant smell) and yellowing.
• BHA (Beta Hydroxy Acid / Salicylic Acid): An exfoliant. Used for its skin benefits, such as exfoliation and acne treatment.

How to add and dissolve:

• EDTA 2Na: This is water-soluble. Dissolve the required amount completely in the water before adding the lye (NaOH). Ensure it is fully dissolved before proceeding to mix the lye solution. Typical usage is around 0.1% to 0.5% of the total soap weight.
• BHT: This is oil-soluble. Add the required amount to your coconut oil and stir until completely dissolved before mixing the oil with the lye solution. Typical usage is very low, around 0.01% to 0.1% of the total oil weight or total soap weight.
• BHA (Salicylic Acid): Salicylic acid is not easily soluble in water or oils directly. It is best dissolved in a small amount of a suitable solvent like isopropyl alcohol or a small portion of your oil before adding it to the soap mixture. Add it at trace (when the soap mixture has thickened slightly but is still pourable), mixing thoroughly. Usage rate in soap is typically 0.5% to 2% of the total soap weight. Be aware that the high pH of soap might affect the efficacy of BHA.

Regarding your experience with EDTA 4Na:

It is unusual that adding EDTA 4Na resulted in faster yellowing and rancidity. EDTA is specifically used to prevent these issues by chelating metal ions that catalyze oxidation.

Possible reasons for your experience could include:

• The quality or purity of the specific EDTA 4Na product you used.
• Interaction with other ingredients or contaminants not mentioned.
• Incorrect usage or concentration.
• Other factors causing rancidity (e.g., quality of coconut oil, exposure to light/air during curing or storage) that coincided with using EDTA 4Na.

EDTA, when used correctly, should help improve the stability and shelf life of your soap by mitigating the effects of metal ions.

I hope this helps with your soap making!