alt="Photo depicts the effect of wax amount on lipstick hardness and structure in selected non-polar oils and oil blends."/>
2.5.4 Influence of Wax-Oil Lipstick Structure on its Deposition and Sensorial Perception
The deposition of simple lipstick containing PE wax and single oils is evaluated as described in the experimental section. The effect of viscosity from selective oils on the lipstick deposit and lipstick hardness is shown in Figure 2.24. It is observed that increasing oil viscosity increases lipstick hardness but decreases the deposit thickness of lipstick on Bioskin. The results obtained are opposite to those for the wax – oil systems containing synthetic wax - polyethylene - polypropylene/ethylene copolymer reported in [33]. In that study, increasing oil viscosity enhanced the hardness of the lipstick and more deposit of lipstick was observed.
The deposit of applied lipstick is also dependent on wax amount and wax type. With low wax amount, the lipstick is softer and thickness of deposit is higher. De Clermond-Gallerande et al. [33] also observed that the thickness, smoother texture and uniformity of applied lipstick were enhanced when low amount of wax was used. In addition, at a fixed wax amount, changing wax type will change the thickness of applied lipstick.
Table 2.8 Effect of wax amount on lipstick hardness and structure in selected polar oils.
Figure 2.24 Effect of the thickness of deposit on lipstick hardness on Bioskin.
Figure 2.25 Effect of oil polarity and oil viscosity on sensorial perception (S+M region is the transition between smooth (S) and moist (M) regions).
The sensorial perception of more than 70 simple lipsticks containing oils with various polarities and viscosities was evaluated by professional formulators. The results show that the sensorial perception is strongly dependent on oil viscosity, but neither on oil polarity nor on hardness of lipstick (Figure 2.25) which is consistent with the conclusions from Abidh and coworkers [34]. When viscosity increases, the sensorial perception changes from being smooth to moist and then sticky. The transition between smooth and moist regions gives a watery feeling that is favored by Japanese consumers.
2.6 Summary
Due to increasing consumer demand for natural cosmetic products, environmental awareness and new regulations in beauty industry, the natural waxes and natural oils have been developed and have replaced the synthetic ones in cosmetic products. In order to achieve the same performance as the non-natural/synthetic products, the understanding of the crystallization of the natural waxes with oils and pigments/fillers is necessary. By using the simplest model containing a non-polar PE wax and various polar oils, we showed that the hardness of the lipstick was affected by both the oil polarity and oil viscosity at a fixed amount of wax. Increasing the oil polarity and viscosity, the oil-wax stick was harder with smaller or close-packed crystals as observed by SEM. These results were found to be very similar to the natural wax-oil gel systems reported in literature. In addition, increasing the oil viscosity, the sensorial perception was observed to change from smooth to watery to sticky, and it did not depend on the oil polarity. From this simple oil-wax model, we can apply these results to modulate the hardness of natural lipstick, its deposit and sensorial perception by selecting the right oil and the right amount of any wax in the formulation.
However, the next challenge for cosmetic scientists is how to reformulate the long-wear, non-transfer cosmetic products using natural film-formers, natural oils, natural color pigments/fillers and natural waxes to achieve the same performance results as the silicone based products.
Acknowledgements
The authors would like to thank E. Tokunaga for technical assistance with the experiments. We would also like to take this opportunity to thank Dr. Stephane Ortiz, and L’Oréal Research and Innovation Department for supporting this work.
References
1. M. Kadui, S. Vishwasrao and S. Singh, Review on natural lip balm, Int. J. Res. Cosmetic Sci., 5, 1-7 (2015).
2. N. P. Chaudhari, N. U. Chaudhari, H. A. Chaudhari, L. A. Premchandani, A. R. Dhanani and S. P. Pawar, A review on herbal lipstick from different natural coloring pigment, Indian J. Drugs, 6, 174-179 (2018).
3. A. A. Bintiyusof, A. B. Ajit, A. Z. Sulaiman and A. Naila, Production of lip balm from stingless bee honey, Maldives Natl. J. Res., 1, 57-72 (2018).
4. A. D. Maru and S. R. Lahoti, Formulation and evaluation of lipstick containing sunflower wax, Int. J. Pharm. Res., 10, 126-130 (2018).
5. A. R. Fernandes, M. F. Dario, C. A. S. de Oliveira Pinto, T. M. Kaneko, A. R. Baby and M. V. R. Velasco, Stability evaluation of organic lip balms, Braz. J. Pharm. Sci., 49, 293-299 (2013).
6. L. Budai, I. Antal, and I. Klebovich, Natural oils and waxes: studies on stick bases, J. Cosmet. Sci., 63, 93-101 (2012).
7. A. I. Blake, E. D. Co and A. G. Marangoni, Structure and physical properties of plant wax crystal networks and their relationship to oil binding capacity, J. Am. Oil Chem. Soc., 91, 885-903 (2014).
8. A. I. Blake, J. F. Toro-Vazquez and H. Hwang, Wax oleogels in: Edible Oleogels, 2nd Edition, A. Marangoni and N. Garti (Eds.), pp 133-171, Elsevier Science, (2018).
9. a. https://www.kosterkeunen.com/personal-care-cosmetic-waxes/ b. http://spwax.com/index.html
10. L.S.K. Dassanayake, D. R. Kodali, S. Ueno and K. Sato, Physical properties of rice bran wax in bulk and organogels, J. Am. Oil. Chem. Soc., 86, 1163-1173 (2009).
11. V. Sabale, P. M. Sabale and C. L. Lakhotiya, In vitro studies on rice bran wax as skin moisturizer, Indian. J. Pharm. Sci., 69, 215-218 (2007).
12. P. Bradford, J. T. Simonnet and J. M. Singer, Aqueous wax dispersions containing volatile solvents, US Patent 10,626,294, assigned to L’Oreal (2020).
13. P. Bradford, J. T. Simonnet, J. M. Singer and H. Samain Aqueous wax dispersions, US Patent 10,413,496, assigned to L’Oreal (2019).
14. J. T. Simonnet, P. Bradford, C. M.S. Shawn and J. M.
