Shower Oil Color Change: Preventing Oxidation with Antioxidants

The issue of shower oil turning darker is most likely due to the oxidation of natural oils in the formula, specifically Sunflower Oil. Natural oils like Sunflower Oil contain unsaturated fatty acids that are prone to reacting with oxygen in the air (oxidation). This reaction can be accelerated by heat, light, or other components in the formula.

Based on your formula and procedure, the color change after 1-2 days suggests oxidation of the Sunflower Oil. Heating the mixture to 70°C, even if not for a long time, can also contribute to accelerating the oxidation process.

How to fix the problem:

1. Add an Antioxidant: This is the primary method to prevent discoloration from oxidation. Antioxidants help inhibit the oxidation reaction of the oils. We recommend using Tocopherol (Vitamin E), a common antioxidant used in oil-based products. Typically, it is used at a concentration of 0.1-1% of the total formula. You should add Tocopherol to the oil phase along with the Sunflower Oil before mixing or heating.
2. Review the Heating Step: If possible, reduce the temperature or duration of heating. Alternatively, you could try mixing the natural oil (Sunflower Oil) and Mineral Oil with the antioxidant first, and then combine this mixture with the heated MIPA and Oil Blender (after the MIPA+Oil Blender portion has cooled down slightly but is still at a temperature suitable for mixing) to minimize direct heat exposure to the Sunflower Oil.
3. Check Raw Material Quality: Although not always the main cause, the quality and freshness of Sunflower Oil, MIPA, Oil Blender, and the fragrance can also affect color stability.

In summary: Adding an antioxidant like Tocopherol (Vitamin E) at 0.1-1% to your formula, along with the Sunflower Oil, is the most recommended way to solve the shower oil discoloration problem.