Improving Stability and Shelf Life of Your Shower Oil Formula

To prevent changes in scent and color and extend the shelf life of your shower oil formula, you should address two main factors: oxidation of the oils and potential microbial growth.

Preventing Oxidation (Scent and Color Stability)

Oils, especially those high in unsaturated fatty acids like Sweet Almond Oil and Grape Seed Oil, are susceptible to oxidation. This process causes them to go rancid, leading to unpleasant odors and discoloration. Your formula already contains Vitamin E (Tocopheryl Acetate), which acts as an antioxidant, but you can enhance protection by adding a more powerful antioxidant.

Consider adding one of the following oil-soluble antioxidants:

• Protec™ OX: A highly efficient synthetic antioxidant. Use at 0.01% to 0.5%. Requires heating to 70-80°C to dissolve.
• Rosemary Oleoresin Extract (ROE): A natural extract with high antioxidant activity. Use at 0.02% to 0.1%. Note that it has a dark color and a distinct scent.
• Dimethylmethoxy Chromanol (1%, Oil Based): More effective than Vitamin E for protecting oils. Use at 1%. Add in the final step and avoid heat.
• Butylated Hydroxytoluene (BHT): A common synthetic antioxidant. Use at 0.01% to 0.1%. Can be heated to aid dissolution.

Choose the antioxidant that best suits your preference for natural vs. synthetic ingredients and consider the potential impact of ROE on color and scent.

Extending Shelf Life (Preventing Microbial Growth)

Microbial growth (bacteria, mold, yeast) occurs in the presence of water. If your shower oil formula is completely anhydrous (water-free), a preservative is generally not needed. However, if the Oil Soap base or any other ingredient introduces water, or if water could be introduced during use, adding a broad-spectrum preservative is essential.

If your formula contains water, consider adding a water-soluble preservative:

• Mild Preserved™ COS: A broad-spectrum, odorless preservative effective in pH 2-8. Use at 0.75% to 1.5%. Add at temperatures below 45°C.
• NaturePreserve™ Ultra: A natural, powder preservative effective in pH 3-6. Use at 0.75% to 2.0%. Do not use with L-Ascorbic Acid.

Assess your formula for water content to determine if a preservative is necessary. If in doubt, adding a preservative is a safer option for extending shelf life.

By incorporating a suitable antioxidant and potentially a preservative, you can significantly improve the stability and extend the shelf life of your shower oil, keeping its scent and color consistent over time.