Let’s stir up some magic in the lab with today’s hot topic: Crafting The Perfect Oil Phase in your Skincare Formulations.

If you have ever wondered why two creams with similar INCI lists feel completely different on skin, the answer lives in the ratios of the oil phase, emulsifier, thickeners. The lipid architecture (among other things) determines slip, cushion, dry-down, glow versus matte finish, perceived richness and the occlusive protection customers sense hours later.

Your formula is like a miniature ecosystem: each component has a role and the blend must be tuned to the formula’s purpose, the pack and the real bathroom it will live in. In this deep dive, we’ll focus on the lipid phase of your emulsions, balms and oil serums to make them feel unmistakably premium and behave beautifully through their shelf life.

Start with the brief: the skin feel you want and the job the product must do

Before you reach for a single oil, define the sensation a customer should notice first and the functional job the product must perform. Is this a fast-absorbing daily serum? A night cream that leaves a protective, cushioned veil until morning? A balm that melts quickly yet avoids greasiness? A hair oil that adds gloss without crispness? That first decision fixes the boundaries for your oil phase: how volatile or substantive it should be, how occlusive the film, how quickly it should reduce tack and what level of shine is desirable. Good lipid design always starts with intent.

Polarity is your compass: place each material where it wants to live

“Oil” is not one thing. Triglyceride oils, esters, hydrocarbons, silicones and natural waxes sit along a polarity spectrum. Polarity affects miscibility, spreading and how an oil interacts with emulsifiers, film formers and actives. Low-polarity materials such as isoalkanes, hydrogenated polyisobutene, squalane and long-chain esters contribute to fast spread, minimal drag and a clean dry-down. Medium-polarity esters like C12-15 alkyl benzoate, coco-caprylate/caprate or diheptyl succinate supply glide and help solubilise UV filters or lipophilic actives without heaviness. Higher-polarity triglycerides like sunflower, sweet almond or avocado oil build cushion and nourishment but can slow absorption if overused. Silicones and silicone-alternatives (for the natural lovers, like me!) add unique slip and surface evenness.

A well-judged cascade of low, medium and higher polarity components gives you elegant application and a controlled finish. Map your chosen oils on a simple low-to-high polarity line and choose a blend rather than one material to avoid single-note flatness. This approach elevates your oil phase from “just oil” to strategic and elegant design.

Volatility, Heat and Polarity Compatibility

Volatility plays a huge role in how an oil phase behaves during both manufacture and wear. Highly volatile materials such as light alkanes, cyclopentasiloxane or certain silicone alternatives can flash off quickly under heat, which means you should always add volatile ingredients below 40 °C during cool-down to preserve their spread profile and prevent unwanted evaporation losses that can alter your oil-to-water ratio or destabilise your emulsion.

When mixing oils with different polarities, balance is key. Low-polarity hydrocarbons dislike very polar triglycerides or esters, and if their ratio is extreme, you may see haziness, phase separation, or even crystal formation as the system cools. This happens because each oil prefers a different environment. To prevent incompatibility, bridge the gap with a mid-polarity ester such as C12-15 alkyl benzoate or coco-caprylate/caprate, which acts as a “translator” between both ends of the polarity spectrum. A well-designed cascade not only stabilises the blend but gives a smoother, more coherent sensory transition on skin.

Absorption time: engineer the spreading and the set

Absorption is part physics, part perception. Customers interpret fast spread and quick set as “light” even when the formula contains meaningful lipids. To tune absorption time combine a fast-spreading volatile or light ester with one or two mid-range emollients and a small percentage of substantive film-former. The fast component lays the product down, the mid component carries the actives, and the substantive element anchors the film so the finish is smooth rather than vanishing to dryness.

In the lab, I time three moments: initial slip in the first five seconds, transition to cushion in the next thirty seconds, and final set by one to two minutes. If your daily moisturiser is still tacky beyond a minute, you should revisit either your lipid balance (and reduce high-viscosity emollients), your humectants (for example, your glycerin content in your water-phase) or your rheology modifiers.

Waxes, fatty alcohols and thickeners: structure that feels elegant

Structure holds an oil phase together but the wrong structure reads as drag or grain. In balms, think in families. Crystalline waxes such as microcrystalline or plant waxes provide a skeleton. Butters like shea or mango fill in body and sensorial bloom. Fatty alcohols like cetearyl alcohol and cetyl alcohol deliver smooth, substantive slip and help stabilise emulsions. Modern oil-gelling agents (such as Viscolid MB or Glyceryl Dibehenate) produce clear, cushiony oil gels without waxy after­-feel.

Let me leave you with my final thoughts!

A balanced oil phase is not a list of favourite oils. It is a system that delivers the exact feel and function you promised in the brief. Use polarity to guide compatibility and solvency. Use spreading cascades to control absorption time. Use film formers to manage occlusion without heaviness. Use waxes, fatty alcohols and rheology modifiers to create elegant structures. Protect the phase with antioxidants and the right packaging.  When you work this way your moisturiser feels intentional, your balm feels modern and your oil serum feels weightless yet satisfying. Retail reviewers notice. Customers finish the bottle. That is the quiet power of a designed oil phase.

Here’s to formulas that work and brands that thrive!
From my lab to yours,

Rose