Addition Timing and Dispersion for Carbomer 2020 and Xanthan Gum in Serum and Sunscreen
Question
I am seeking guidance on the proper incorporation of two thickening agents in complex formulations:
1. Carbomer 2020 (EasyDisperse, Electrolyte Tolerance, Long-flow)
For use in serum formulations (both hot and cool process) and W/O or W/S waterproof sunscreen systems, what is the correct step for addition?
- What is the ideal temperature range for addition?
- Is resting time required for full hydration/swelling after addition?
- Should it be added early (after dissolving EDTA), mid-process, or late (before adjusting pH with AMP/Citric Acid)?
2. Xanthan Gum
In the water phase of a waterproof sunscreen containing:
- Humectant & Glycol
- Whitening/Anti-Acne Active
- Hydration & Soothing Complex
- Antioxidant
- Preservative system
What is the correct step for adding Xanthan Gum within this complex water phase?
Answer
1. Carbomer 2020 (EasyDisperse, Electrolyte Tolerance, Long-flow)
Carbomer 2020 is an "EasyDisperse" type, meaning it disperses quickly, and its "Electrolyte Tolerance" makes it suitable for complex formulas like serums and sunscreens. However, like all Carbomers, it requires proper hydration before neutralization to achieve full viscosity.
| Aspect | Procedure |
|---|---|
| Timing in Water Phase | Early Stage (After EDTA, Before Actives) |
| Specific Steps | 1. Add water to the main vessel. 2. Dissolve the chelating agent (e.g., EDTA). 3. Slowly sprinkle Carbomer 2020 onto the surface of the water while stirring (moderate speed). 4. Allow the Carbomer to fully hydrate. |
| Hydration/Swelling | Yes, required. Even EasyDisperse types benefit from 15-30 minutes of mixing or resting to ensure all particles are fully wetted and hydrated. This is crucial for maximum thickening efficiency. |
| Temperature | Cool Process (Ideal): Room temperature (25-30°C) is best for dispersion and hydration. Hot Process: It can be added to the cold water phase and heated, or added after the water phase has been heated and cooled down slightly (e.g., below 60°C) to ensure easy dispersion before the emulsion process. |
| Neutralization (AMP/Citric Acid) | Final Step. Neutralization with a base like AMP (Aminomethyl Propanol) is the last step to activate the Carbomer and achieve viscosity. This should be done after all other water-soluble ingredients (actives, humectants, preservatives) are added and dissolved, and often after the emulsion has been formed (especially in W/O or W/S systems). Citric Acid is an acid and is used to lower the pH if the AMP addition makes the formula too alkaline, not to thicken it. |
2. Xanthan Gum in the Water Phase
Xanthan Gum is a natural polysaccharide used for thickening and emulsion stabilization. It must be properly dispersed to prevent clumping ("fish eyes").
| Aspect | Procedure |
|---|---|
| Timing in Water Phase | Early Stage (Before Actives) |
| Specific Steps | Xanthan Gum should be added very early in the water phase, before high-electrolyte ingredients (Whitening/Anti-Acne Actives, some Antioxidants, Preservative salts). |
| Dispersion Method | Pre-Disperse in Glycol/Humectant. The best method is to mix the Xanthan Gum with a non-solvent like Humectant & Glycol (e.g., Glycerin, Propylene Glycol) from your formula to create a slurry. Then, add this slurry to the water phase with high-shear mixing. This prevents clumping and ensures rapid, uniform hydration. |
| Order of Addition | 1. Water + EDTA. 2. Xanthan Gum Slurry (mixed with Glycol/Humectant). 3. Allow to hydrate (15-30 minutes). 4. Add remaining water-soluble ingredients (Whitening/Anti-Acne Active, Hydration & Soothing Complex, Antioxidant, Preservative system). |
