46 WAXES & BUTTERS
wide range of solidification points, can lead to softer gels, due to disruptions in the network. Gels can be characterised in a variety of
ways, depending on the desired end use. Such characteristics can include physicochemical properties, rheological properties, stability, human safety and structural features.6
For our purposes,
and generally in the cosmetic industry, simple gel hardness or strength can be enough information. There are some variations when it comes to measuring gel strength, but most methods involve the use of a penetrometer, which can measure the distance travelled by a weighted cone or needle (depending on the formula and the sensitivity required) through the gel in a given time, which is recorded in 0.1 mm increments. More distance indicates a softer gel; less distance indicates a harder gel. Understanding gels and gel strengths is a very
important tool in anhydrous cosmetic formulation. Furthermore, the ability to collect and document different gel strengths and organise the data in a meaningful way can save a lot of trial-and- error time when it comes to formulation design. Gel charts published here are built by plotting penetration distance on the y-axis vs. a variable parameter on the x-axis (% wax, % oil, % other additive, or wax type). By overlaying different series on the same chart, we can see how the same wax behaves in different oils or how different waxes behave in the same oil.
Anhydrous formulas with sunflower wax Sunflower gel chart: the foundation To build Figure 1, ten cosmetic oils were selected based on their different chemical functionalities and current popularity of use (Mintel, 2020). Each oil was structured using increasing levels of sunflower wax, and cone penetration values were measured and recorded. In Figure 1, we easily see that sunflower wax
is compatible with all oil mediums tested, and makes similarly strong gels in most of them, with the exception of jojoba oil and, to a lesser degree, paraffin oil and octyl palmitate. The numbers form the y-axis tell us the
penetration of each simple gel, but they can also give us an idea of what to expect when making finished anhydrous products in terms of hardness and structure. To better ‘connect’ the penetration numbers to finished formula textures, we provide Table 1 with realistic examples. Most typical cosmetic anhydrous formulations
will fall into the 15 - 40 dmm range (60 - 100 dmm if using a needle). In Figure 1 we see that 7 - 10 % sunflower wax can achieve these numbers, almost regardless of the oil medium, proving how efficient it is.
Comparison to other structurants In order to better understand how sunflower wax compares to other structuring waxes used routinely in personal care, we designed the following study. First, from Figure 1, we selected several oils to study independently: Castor oil, caprylic/capric triglyceride (CCT), coconut oil, octyl palmitate, and jojoba oil. Aside from sunflower wax, six more structurants
were selected based on popularity in anhydrous systems (Mintel, 2020). The four oils described above were structured with increasing amounts
PERSONAL CARE March 2021 40-70 30-40 15-30 <15 100-200 80-100 60-80 <60
Soft/medium gels, require some “digging”
Stick with ability to propel/repel, with high payout
Stick with ability to propel/repel, with medium payout
Hard sticks or bars with low payout, need to be warmed or rubbed
TABLE 1: SUNFLOWER WAX CHARACTERISTICS.
Cone penetration range (dmm)
>150 70-150
Needle penetration range (dmm)
>300 200-300 Structure description Flowable Soft gels, easy to scoop Formula examples
Facial oils, serums Ointments, jellies
Pot lip balms, harder body balms, pot make-up
Deodorants, mineral sunscreens, softer stick make-up
Classic lip balms and lip sticks, pencils, organic sunscreen sticks
Hair and body bars
Sunflower Wax ■ Ozokerite■ Polyethylene ■ Synthetic Wax ■ Beewax ■ Carnauba Wax ■ Candelilla Wax ■
300 250 200 150 100 50 0
0
5
10 Wax% Figure 2: Structurant Comparison A - Gel Strength in CCT.
of each wax, and cone penetration values were recorded. Castor oil was eliminated from the study due to incompatibilities observed when structuring with petrochemical waxes. Jojoba and coconut oil are not shown due to being very similar to CCT. Results in CCT as well as in octyl palmitate are presented here (Fig 2 and 3 respectively). In Figure 2, we see that sunflower wax is
equally effective at structuring CCT as synthetic wax, slightly better than ozokerite, polyethylene, and candelilla wax, and much better than beeswax and carnauba wax. Meaning, to achieve a gel with a cone penetration of 50 dmm, we only need 5% sunflower wax, less than if we were using ozokerite or beeswax (7% and 10% needed, respectively). In Figure 3, we can see how much more difficult
it can be to structure octyl palmitate. Beeswax and carnauba wax were not effective at all, while sunflower wax was the most effective of all the
waxes. In this case, to achieve a gel with a cone penetration of 50 dmm, we would need 7% sunflower wax, less than if we were using ozokerite or polyethylene (10%) and much less than candelilla wax (15%).
Replacing petrochemicals with sunflower wax All the data so far points to the same conclusion: Sunflower wax is the most effective structurant regardless of the oil medium; more so than petrochemical structurants which have been used historically for their reliability and robustness. The next logical question is: Can sunflower wax
be a replacement for structuring petrochemical waxes in finished formulations? The gel chart data certainly looks optimistic; however, we know that the complexity of finished formulations could lead to a different conclusion. Making replacements
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Penetration (dmm)
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