21 Bottle Your Sustainability Goals – Minimize
excluded these applications from their 2023 limits on VOCs due to the advocacy by the
Personal Care Product Council and the Personal Care industry.
The GWP is a metric that enables comparisons of the warming impacts of various gases. It
measures the amount of energy that the emissions of one ton of gas will absorb over a specific
period, relative to the emissions of one ton of carbon dioxide (CO
2
)over that period, with
one hundred years being the typical time frame used for GWPs. GWPs provide a common
unit of measure, allowing analysts to combine emissions estimates of different gases and
policymakers to compare emissions reduction opportunities across sectors and gases.
In the personal care industry, the four common VOC solvents used are ethanol, isobutane,
propane, and butane. Carbon dioxide is used as the common unit of measure. As we have
seen with esterification, the feedstock utilized influences the Global Warming Potential.
For instance, ethanol, which is commonly used in aerosol applications, can have a GWP
ranging from 0.5 to 5.5 CO
2
equivalents, depending on the initial feedstock and production
process. (Figure 13)
SPRAY SUNSCREEN CASE STUDY
The sunscreen sprays depicted in Figure 14, EK-6127-1254 (62% VOC) and EK-6127-1255
(55% VOC), were formulated using a filter composition comprising Homosalate (10%),
Figure 13. VOC examples are affected by feedstocks.
Figure 14. Spray sunscreen.

22 JOURNAL OF COSMETIC SCIENCE
Ethylhexyl Salicylate (5%), Octocrylene (4%), and Butyl Methoxydibenzoylmethane (3%).
The initial formulation contained 62% ethanol, which was reduced to 55% by incorporating
Isoamyl Laurate. The use of Isoamyl Laurate was based on its physicochemical properties,
such as spreadability, which could mimic the behavior of ethanol in this matrix.
The spreadability of the formulated system was reviewed using an internal system utilizing
polypropylene substrate with a dosing level of 50 µl. To evaluate the spreading properties,
a polypropylene film was placed on a flat glass plate. Measurements (mm) were taken at
15 seconds, 30 seconds, 1 minute, and 5 minutes. The area, A =πr2, of the spreading was
calculated at each time interval. Results are shown in Figure 15.
The internal spray sunscreens EK-6127-1254 (62%) and EK-6127-1255 (55%) exhibited
spreading behavior at 30-second, 1-minute, and 5-minute intervals that remains constant
(∼950mm2). A market sunscreen spray remained constant for all four time intervals
(∼313mm2).
The gloss attributes of each sunscreen spray were evaluated. Gloss measurements were
taken on the inner volar forearm at a concentration of 2 mg/cm2 using a Zehntner ZGM
1130. The gloss angle was 85°C. In vivo gloss measurements were repeated five times for
each sample at 1-minute and 5-minute time intervals. The samples evaluated were Isoamyl
Laurate made with responsibly sourced palm and enzymatic processing, EK-6127-1254
(62% Ethanol), and EK-6127-1255 (55% Ethanol). The results are shown in Figure 16.
Isoamyl Laurate showed a 22% reduction in gloss at 5 minutes. We believe this reduction
in gloss is due to the branched geometry of the molecule, which enhances absorption, and
the low surface tension and low viscosity that result in high spreadability.
We also observed that the addition of 7% Isoamyl Laurate to formula EK-6127-1255 resulted
in a reduction in gloss. The sunscreen filters used in this system have high refractive indices
(1.5), and high refractive index ingredients produce a high gloss on substrates like skin
and hair. If the individual filters were to come out of solution, they would appear to be very
glossy on the skin surface. We believe that due to the medium polarity of Isoamyl Laurate,
this emollient is maintaining solution homogeneity, resulting in a lower average refractive
index of the solution, and producing a lower gloss.
Figure 15. Spreadability data for the internal spray sunscreens EK-6127-1254 (62%) and EK-6127-1255
(55%) and a market sunscreen spray.