Thickening Lotion with Vitamin C

Adding Vitamin C, especially L-ascorbic acid, to a lotion can significantly lower the pH. Many common thickeners are sensitive to low pH and lose their ability to thicken, causing the lotion to become thin. The large amount of powder added can also contribute to disrupting the lotion's structure.

To thicken your lotion while maintaining the effectiveness of the Vitamin C, you need a thickener that is stable in acidic conditions.

Based on the ingredients you are using:

• Vitamin C (L-ascorbic acid) (Ultra-Fine) is most stable at a low pH, typically between 2.0-4.0 (with cosmetic formulas needing to be pH 3.5 or higher).
• Ascorbyl Glucoside (AA-2G Stabilized Vitamin C) is stable in a pH range of 6.5-6.8.

Combining these two forms of Vitamin C means your final lotion pH will likely be in the acidic range required for L-ascorbic acid (pH 3.5-4.0), which is outside the optimal stability range for Ascorbyl Glucoside. While you mentioned getting good results, be aware of this pH conflict which might affect the long-term stability of the Ascorbyl Glucoside.

For thickening a lotion in this acidic pH range, Xanthan Gum is a suitable option. Xanthan Gum is a polysaccharide thickener that is stable over a wide pH range, including acidic conditions, and is commonly used in cosmetic formulations.

There are different types of Xanthan Gum available, such as:

• Xanthan Gum (clear gel type, smooth texture)
• Xanthan Gum (clear gel type, normal texture, 200 Mesh)
• Xanthan Gum (clear gel type, normal texture, easy to spread)
• Xanthan Gum (clear gel type, normal texture, 80 Mesh)

You can add a small percentage (typically 0.1-1%) of Xanthan Gum to the water phase of your lotion formulation. It needs to be properly dispersed and hydrated to thicken effectively. It's best to disperse it in a small amount of glycerin or oil before adding it to the water phase to prevent clumping, then mix thoroughly until a gel forms before combining with the rest of your lotion ingredients.

Using an acid-stable thickener like Xanthan Gum should help restore the desired viscosity to your lotion without negatively impacting the Vitamin C, provided the pH is kept within the acceptable range for the Vitamin C forms you are using (primarily considering the L-ascorbic acid's requirement for a low pH). Always check the final pH of your formulation.