How to Create Stable Cosmetic Emulsions With a Lab Homogenizer
Researchers developing new cosmetic formulations for consumer markets often work with immiscible ingredients resisting transformation to stable emulsions important to lotions, crèmes and similar products designed to be absorbed by the skin. We emphasize stable emulsions because cosmetics that separate in the jar are a sure sign of product failure. This post describes how researchers can create stable cosmetic emulsions with a lab homogenizer.
- Definitions of immiscible and emulsion
- The value of lab homogenizers in cosmetic research
- Lab homogenizer processing tools for cosmetic research
- Suggestions to match lab homogenizers to sample size
- Other options for creating cosmetic emulsions
Immiscible and Emulsion Defined
You may already know this but if not,
Google defines immiscible as “not forming a homogeneous mixture when added together.” Perfect example: mix up salad dressing ingredients using oil and vinegar. In a few minutes they separate.
Google defines emulsion as “a fine dispersion of minute droplets of one liquid in another in which it is not soluble or miscible.” Perfect example: homogenizing milk to blend the milk and cream so they do not separate.
The Value of Lab Homogenizers in Cosmetic Research
Cost of ingredients is an important consideration when embarking on researching and developing new cosmetic formulas that can include not only creams but desirable when developing shampoos, toothpaste, sunscreens, lipsticks……etc.
This suggests that small sample sizes are desirable allowing emulsifying and similar homogenizing procedures to be accomplished in small containers such as test tubes and small beakers.
That’s why lab homogenizers play a critical role in the creation of new cosmetic blends. They are able to produce stable cosmetic emulsions not only with small sample sizes but also able to work with larger sample sizes during scale-up to pilot plant then production plant levels .
These compact research tools provide product development personnel a wide choice of processing tools described in the next section.
Lab Homogenizer Processing Tools for Cosmetic Emulsions
The Drive Motor
All lab homogenizers have one thing in common: the drive motor. While electric drive motors are most common, air-powered drive motors are available for researchers working where volatile fumes may occur. CAT Scientific drive motors are capable of controllable speeds up to 35,000 rpm depending on models.
The homogenizer drive motor powers the rotor-stator configuration (the generator) that performs the mixing, blending and emulsifying action reducing cosmetic ingredients to the desired form.
Generators come in several configurations, each optimized to do specific tasks. Let’s look at these components:
Rotors, as the name implies, rotate at the speed controlled by the operator and are attached by a shaft to the drive motor. This is similar to a drill bit fitted into a power drill.
Rotors have specially machined sharp teeth designed for specific purposes.
Rotors fit into the aptly named stationary stator with knife-edged slots that are designed specifically to interact with the rotor teeth configuration. Stators are screwed onto a shaft (see below).
When the homogenizer is in operation samples are drawn up into the rotor and violently propelled against the stator. This interaction provides the high-speed sonic mixing, slicing and emulsifying function.
Generators are designed to process viscous, low viscosity and fine samples and samples requiring cutting (knife) applications. These are describe in our sheet on Dispersing Tool Applications .
The shaft, the third component of a cosmetic homogenizer, attaches the generator to the drive motor. Shafts are available in several lengths and diameters depending on the drive motor model and the generator model(s).
Suggestions to Match Homogenizes to Sample Size
Scientists at CAT Scientific have assembled a stable of lab homogenizers that meet the majority of requirements for researchers engaged in developing new cosmetic formulations. Examples include:
- Samples 0.1ml – 1 liter X120 handheld homogenizer
- Samples 0.1ml – 2 liters X330 homogenizer
- Samples 0.1ml – 5 liters XP28 air driven homogenizer
- Samples 500 ml – 20 liters X1740 homogenizer
Homogenizers are also offered with fixed and variable speed and different power options in terms of watts. Check our pages on homogenizer drives to learn all about the options available to lab researchers involved in developing new cosmetic formulations.
Other Options for Cosmetic Lab Homogenizing
While particle size reduction will occur in a homogenizer generator, a special device called an AX60 analytical mill is a great tool for reducing material to a manageable particle size before adding it to the sample.
It couples with a CAT 1,000-watt homogenizer drive motor and consists of a two-part dustless chamber 1holding up to 180 cc of the sample to be pulverized.
Top and bottom portions of the analytical mill are coupled then clamped together to provide a dust tight assembly. Both are equipped with ports to circulate a cooling medium. Pulverizing is accomplished with stainless steel or silicon carbide grinding blades.
Other Cosmetic Research Processing Options
In line or closed-loop processing is accomplished using CAT DK30 or DK40 flow through chambers. Operate the homogenizer drive motor in much the same way you would for standard emulsifying and dispersing.
Material is drawn through clamped tubing into the chambers, processed by the generator then discharged through clamped tubing either back to the beaker or to another container.
The drive motor models determine processing capacity but hold time in the chambers can be controlled by restricting the outlet tube. For more info see our post on flow through chambers.
Caution: Generators must be immersed in the sample before the drive motor is turned on at the lowest speed then ramped up to the desired speed.
Keep the generator at least 10 mm above the bottom of the sample container and mount it at an offset to avoid creating a vortex.
We strongly suggest that researches do not manually hold the homogenizer but instead use the supplied mounting equipment. This also avoids the possibility of accidently splashing contents out of the container or breaking the container.