Preview: Master thesis
Oil absorption of Upsalite®
The oil absorption speed and uptake mechanism of Upsalite was compared to one of the best performing sensory modifying cosmetic ingredients in the market – porous, spherical silica. According to the vendor, this silica has a very strong absorption capacity for oil and water, significantly reducing residual oiliness, greasiness and stickiness of formulations. As shown in this study, these properties are equally inherent to/improved by Upsalite which in addition is compliant with the COSMOS Standard and without animal origin, as verified by ECOCERT GREENLIFE.
Results: Oil absorption capacity on macro- and microscale
However, high oil absorption may not always correspond to efficient removal of oil/sebum from the skin. This was evident in the microscopic study of pure Upsalite and the porous spherical silica where the appearance of raw and 0.75 g / g oil loaded materials were compared (Figure 1 a-d). A scanning electron microscope, with a resolution well below the micro meter scale, was used to clarify any changes of topology of the materials upon oil loadingiii. The oil can be identified by a shine or whitening effect and by change in the surface appearance and particle shape. It was clear that large lumps of oil were formed outside and on the surface of the porous spherical silica particles. The Upsalite particles remained dry and matte without any visible oil residing outside or on the particles. The formation of lumps or oil aggregates observed for the porous spherical silica at this relatively low level of oil absorption suggests that the mechanism of oil uptake is not driven by capillary forces. On the contrary, the matte appearance of Upsalite with no major changes of particle shape suggests a complete absorption of oil into the Upsalite particles.
Figure 1. Scanning electron microscope images of (a) bare Upsalite, b) bare porous spherical silica, c) Upsalite loaded with 0.75 g oil/g material and d) porous spherical silica loaded with 0.75 g oil/g material.
Oil absorption speed
In addition the oil absorption, speed of absorption was measured for Upsalite and porous spherical silica. The results were remarkably different. It took Upsalite less than 5 min to absorb all of the oil, whereas porous, spherical, silica took 40 min to absorb the same amount of oil. The speed of oil absorption gives information on the mechanism of oil absorption and degree of hydrophobic character (preference to oil) of the material. The results showed an instant mode of action for Upsalite oil absorption and a considerably delayed action for Silica.
In summary, this new data can be used to substantiate the claims Instant mattifying effect and Complete removal of excess sebum on skin for Upsalite in cosmetic products.
Time lapses of Upsalite (left) and porous spherical silica (right) oil speed uptake.
i. The oil uptake method was adapted from the standard test method ASTM D281-95 for oil absorption of pigments by spatula rub-out.
ii. Bamford, E. et al. (2020) ‘Mesoporous magnesium carbonate for use in powder cosmetics’, International Journal of Cosmetic Science, pp. 1–11. doi: 10.1111/ics.12670.
iii. High-resolution Field Emission Gun Scanning Electron Microscope Zeiss Merlin (Zeiss, Germany). An acceleration voltage of 2 keV and a probe current of 80 pA was used and samples were mounted onto Al stubs using conducting carbon tape.
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