Gentle Shower Gel Formulation for Oily, Sensitive Skin Prone to Irritation

Hello,

Thank you for reaching out and providing such detailed information about your skin concerns and previous attempts at making shower gel. It sounds like you have very sensitive skin that reacts to common surfactants like sulfates and potentially KOH, experiencing dryness, itching, and irritation despite having oily skin.

Based on your experience with the Oil Soap formula causing warming and irritation, and the staff's feedback, it seems likely that your skin is sensitive to MIPA-Laureth Sulfate (the main component of Oil Soap) and possibly also to high concentrations of a single surfactant like Lauryl Glucoside, even though your original formula was less irritating than commercial ones.

To address your needs for a gentle, effective, non-drying, and viscous shower gel suitable for oily, sensitive skin, I recommend trying a formula that uses a blend of mild surfactants and incorporates ingredients for skin conditioning and thickening.

Here is a proposed formula concept:

• Lauryl Glucoside (ID 177): 15% - A very mild non-ionic surfactant, slightly lower concentration than your original formula.
• Coco Betaine (ID 160): 5% - An amphoteric surfactant that is mild, helps boost foam, and can improve the mildness of anionic/non-ionic blends.
• Glycerin (ID 143): 20% - A humectant to help retain moisture in the skin.
• WaterLock™ (Polyquaternium-51) (ID 258): 3% - A skin-conditioning polymer that remains on the skin after rinsing, providing long-lasting hydration and reducing dryness and irritation caused by surfactants, as suggested by the staff.
• SugarThick™ (PEG-120 Methyl Glucose Dioleate) (ID 510): 1.5% - A non-ionic thickener that is effective in surfactant systems and can help achieve a gel consistency.
• Water: 55.5% - The base of the gel.
• Citric Acid (ID 153): q.s. to pH 5.5-6.0 - To adjust the pH to be skin-friendly.

Instructions:

1. Combine Water, Lauryl Glucoside, Coco Betaine, Glycerin, WaterLock™, and SugarThick™. Mix gently until homogeneous. Avoid vigorous mixing to prevent excessive foam.
2. Measure the pH of the mixture.
3. Slowly add a solution of Citric Acid (e.g., 20-30% solution in water), mixing well after each addition, until the desired pH of 5.5-6.0 is reached.
4. (Optional) Add a preservative according to the supplier's instructions to prevent microbial growth, as the formula contains water.
5. (Optional) Add fragrance or essential oils if desired, ensuring they are suitable for sensitive skin and used at a low concentration.

Why this formula?

• The combination of Lauryl Glucoside and Coco Betaine provides effective cleansing while being gentler than a single surfactant at high concentration.
• Glycerin and especially WaterLock™ help to hydrate the skin and reduce the feeling of dryness and irritation after washing. WaterLock™ is particularly useful as it stays on the skin.
• SugarThick™ provides the desired gel viscosity.
• Adjusting the pH to 5.5-6.0 is important for maintaining the skin's natural barrier function.

Regarding the cost, while I cannot provide exact pricing, the ingredients proposed are commonly used and generally available. However, achieving a cost below 50 THB/100g might be challenging depending on the specific source and quantity purchased.

It is highly recommended to test this formula on a small area of your skin first to ensure there is no irritation before using it on your entire body.

I hope this helps you create a shower gel that is comfortable and effective for your sensitive skin!