Exploring the application of Ethylcellulose oleogels in skin foundations

The growing global market for waterless cosmetics spans skincare, haircare and makeup. Ethylcellulose (EC) oleogels have been utilised as bases in pigmented lip products, but not in complexion cosmetics. The aim of this project was to explore potential applications of EC oleogels in skin foundations.

Oleogels were prepared by heating EC and selected emollients to 140º C, while stirring until homogenous. The emollients used were Castor Oil (CO), Ethylhexyl Palmitate (EHP) and Coco-Caprylate/Caprate (CCC). Foundations were prepared by mixing pigments (Iron Oxides and Titanium Dioxide) with the EC-emollient mixture at 140º C and, when applicable, adding Dimethicone (DM) or Caprylyl Methicone (CM) at 85º C.

Samples were tested rheologically via shear rate sweep (0.001 – 100.00 s-1), amplitude sweep (strain 0.01 – 100.00%; 1.00 Hz) and frequency sweep (0.10 – 10.00 Hz; 1.00 Pa within LVR) methods, using an oscillatory rheometer with a parallel plate geometry. An immersion/de-immersion method using a texture analyser was employed to test the textural parameters of selected samples.

It was found that both single EC-CO oleogels and combined EC-CO/EHP/CCC oleogels, at various EHP-CCC ratios, were stable. The results showed that EHP increased oleogel complex modulus (rigidity), while CCC had the opposite effect. Incorporating pigments resulted in stable EC-CO/EHP/CCC oleogel foundations with increased rigidity. Including DM or CM in either oleogels or foundations resulted in stable formulas with lower phase angle (reduced elasticity) and reduced stickiness. Interestingly, the addition of both DM and CM produced predominantly elastic systems at low frequencies, whereas all other samples were viscous over the whole frequency range. Therefore, DM and CM could support long-term storage stability, which is particularly important in products with suspended solid pigments.

EC-CO/EHP/CCC oleogels have shown considerable potential as foundation bases, especially when DM or CM is included. With additional textural and sensory optimisation, these prototypes could meet consumer acceptance.