Formulation and Mixing Guidelines for ReadyMix™ Iron Oxides in W/O Cream
Question
I am formulating a thick cream (not a fluid) using ReadyMix™ Iron Oxides and would like to clarify the mixing process and stability. My formulation uses the following specific products and components:
Ingredients
- Pigments:
ReadyMix™ Iron Oxides Black (Polyglyceryl-2 Triisostearate Based)ReadyMix™ Iron Oxides Red (Polyglyceryl-2 Triisostearate Based)ReadyMix™ Iron Oxides Yellow (Cyclopentasiloxane Based)
- Emulsifiers (Oil Phase):
Lauryl PEG-9 PDMSandCetyl PEG/PPG-10/1 Dimethicone - Water Phase:
Disodium EDTA0.2%,Magnesium Sulfate1%,Sodium Citrate0.15%,Xanthan Gum0.15%, andCarbomer U210.25%.
Questions
- Can these ReadyMix™ colors be mixed at room temperature, or is heating to 75°C required every time? What are the recommended mixing speeds and durations?
- What is the optimal order of addition within the oil phase to achieve the best results?
- In my current process, I mix the oil phase at a low speed until uniform, then add the emulsifiers (
Lauryl PEG-9 PDMS+Cetyl PEG/PPG-10/1 Dimethicone), and finally combine it with the water phase. Given the presence of electrolytes (Magnesium Sulfate) and thickeners (Carbomer U21) in my water phase, is this process viable, or will it cause stability issues?
Answer
Regarding your questions about using ReadyMix™ Iron Oxides in your formulation, here are the detailed recommendations:
1) Temperature and Mixing Speed
- Temperature: ReadyMix™ Iron Oxides are pre-dispersed in oil or silicone bases. They can be mixed at room temperature (Cold Process). You do not need to heat them to 75°C unless other ingredients in your oil phase (such as waxes) require melting.
- Mixing Speed: Since the pigments are already fully dispersed, you can use low to medium speed stirring to incorporate them into the oil phase. High-speed homogenization is not required for the color dispersion itself, but it will be necessary later when forming the final emulsion.
2) Order of Addition in the Oil Phase
- Best Practice: Mix the ReadyMix™ colors into the oil/silicone phase first and stir until the color is uniform.
- Once the color is evenly distributed in the oil phase, you can then add your emulsifiers (Water-in-Oil EZ™ and Lauryl PEG-9 PDMS). This ensures the pigments are properly trapped in the external phase of your Water-in-Oil (W/O) system.
3) Process and Formulation Stability Concerns
Your proposed process of adding the water phase to the oil phase is correct for a W/O system. However, there are critical points regarding your ingredients:
Carbomer U21 vs. Magnesium Sulfate:
- Your water phase contains Magnesium Sulfate (1%), which is an electrolyte essential for stabilizing W/O emulsions made with Water-in-Oil EZ™.
- However, Carbomer U21 is extremely sensitive to electrolytes. The presence of Magnesium Sulfate will cause the Carbomer to lose its viscosity and fail to form a gel, which can lead to formula instability or separation.
- Recommendation: To achieve a thick cream texture in a W/O system, it is better to remove the Carbomer and instead increase the amount of Xanthan Gum or use an oil-phase thickener like Hectorite Gel or waxes.
Emulsification Speed:
- While low speed is fine for mixing the color, the step where you add the water phase into the oil phase requires high-speed mixing (High Shear/Homogenizer) while gradually adding the water. This is necessary to create small water droplets for a stable and thick cream. If the speed is too low during this stage, the cream may be thin or separate later.
Summary: You can proceed at room temperature. Mix the color into the oil first. Crucially, remove Carbomer U21 from the water phase if you are using Magnesium Sulfate, and use high-speed mixing during the final emulsification (adding water to oil) to ensure stability and the desired thickness.
Relevant Products:
