Soap Formulation: Ingredient Stability, Percentage Calculation, and Herb Powders

Based on your question and the feedback provided, here's how to calculate ingredient percentages for your soap and some important points about the ingredients you listed:

Calculating Percentages
The standard way to calculate ingredient percentages in cosmetic formulations is by weight/weight (w/w). This means:

Weight of Ingredient = (Target Percentage / 100) * Total Weight of Formulation

For example, if you want to make 1000g (1kg) of soap and add an ingredient at 1%, you would add 10g of that ingredient (1/100 * 1000 = 10).

Suitability of Your Ingredients for Soap
As the staff correctly advised, a high-pH soap base is not suitable for many active ingredients:

• Alpha Arbutin & Vitamin C (L-ascorbic acid): These ingredients are unstable and will degrade in the high-pH environment of soap, making them ineffective.
• Herbal Powders (Turmeric, Tamarind, Plai): While natural, the beneficial compounds in these powders are not effectively absorbed by the skin when used in a wash-off product like soap. They may primarily serve as colorants or mild exfoliants.
• Phenoxyethanol: This is a preservative. If you choose to use a preservative, calculate the amount based on the supplier's recommended usage rate (often 0.5-1%) and your total batch size.
• SmellSorb (Zinc Ricinoleate): This is an odor absorber. Check the supplier's recommended usage rate for stability and effectiveness in soap.

Recommendation:
Given the instability of many beneficial ingredients in soap, consider using them in leave-on products (like lotions or creams) where they can be effective. For your soap, focus on ingredients that are stable in high pH and serve the primary function of soap (cleansing), perhaps adding stable colorants, fragrances, or mild exfoliants if desired.