The lipid phase of a cosmetic formula does far more than simply moisturise the skin. The specific combination of carrier oils, butters, and waxes you choose determines the skin feel of your finished product, its stability on the shelf, its suitability for different skin types, and its ability to deliver active ingredients effectively. Selecting lipids by price or availability alone, without understanding their fatty acid composition and functional properties, produces formulas that are either too heavy, too greasy, too prone to oxidation, or simply not suited to their intended application.
This guide covers the key categories of lipid ingredients used in cosmetic formulation, their functional properties, and how to select and combine them for specific product types and skin types.
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Understanding Fatty Acid Composition
Carrier oils are composed primarily of triglycerides, which are esters of glycerol and three fatty acid chains. The fatty acid composition of an oil determines almost everything about its behaviour in a formula: how quickly it absorbs, how occlusive it is, how prone it is to oxidation, and how it feels on the skin.
Fatty acids are classified as saturated (no double bonds), monounsaturated (one double bond), or polyunsaturated (two or more double bonds). Saturated fatty acids are highly stable and resistant to oxidation. Polyunsaturated fatty acids are less stable and more prone to rancidity, but they are also more biocompatible with the skin's own lipid barrier and are associated with better absorption and skin feel in lightweight formulas.
| Fatty Acid | Type | Key Oils | Skin Feel | Oxidation Risk |
|---|---|---|---|---|
| Lauric (C12:0) | Saturated | Coconut, Palm Kernel | Light, fast-absorbing | Very low |
| Stearic (C18:0) | Saturated | Shea Butter, Cocoa Butter | Rich, occlusive | Very low |
| Oleic (C18:1) | Monounsaturated | Olive, Argan, Avocado | Rich, penetrating | Low |
| Linoleic (C18:2) | Polyunsaturated (Omega-6) | Rosehip, Evening Primrose, Hemp | Dry, fast-absorbing | High |
| Alpha-Linolenic (C18:3) | Polyunsaturated (Omega-3) | Flaxseed, Chia | Very dry, fast-absorbing | Very high |
| Ricinoleic (C18:1-OH) | Hydroxy fatty acid | Castor Oil | Heavy, glossy | Low |
Carrier Oils: Selection by Skin Type and Product Application
Oily and acne-prone skin benefits most from oils high in linoleic acid (Omega-6). Research has shown that acne-prone skin is often deficient in linoleic acid relative to oleic acid, and that topical application of linoleic-rich oils can help support the appearance of clearer skin. Rosehip Oil, Hemp Seed Oil, and Evening Primrose Oil are all high in linoleic acid and are well-suited to oily and combination skin types.
Dry and mature skin benefits from oils high in oleic acid, which penetrates the skin more readily and provides a richer, more occlusive feel. Argan Oil, Avocado Oil, and Marula Oil are all high in oleic acid and are well-suited to dry and mature skin types. Jojoba Oil, technically a liquid wax rather than a triglyceride oil, is unique in that it is composed primarily of wax esters that closely resemble the skin's own sebum, making it suitable for all skin types.
Sensitive skin benefits from oils with a high saturated fatty acid content, which are less likely to cause irritation than highly unsaturated oils. Shea Butter (high in stearic and oleic acid) and Coconut Oil (high in lauric acid) are both well-tolerated by sensitive skin, though Coconut Oil has a comedogenic rating of 4 and should be used cautiously in facial formulas for acne-prone skin.
Butters: Functional Properties and Usage Rates
| Butter | INCI Name | Melting Point | Usage Rate | Key Properties |
|---|---|---|---|---|
| Shea Butter | Butyrospermum Parkii Butter | 32–38°C | 2–15% | Rich in stearic and oleic acid; excellent skin feel; widely tolerated |
| Cocoa Butter | Theobroma Cacao Seed Butter | 34–38°C | 2–10% | High stearic content; firm texture; can cause graininess if cooled too rapidly |
| Mango Butter | Mangifera Indica Seed Butter | 34–38°C | 2–10% | Similar to shea; lighter skin feel; good for body care |
| Kokum Butter | Garcinia Indica Seed Butter | 38–40°C | 1–5% | Very hard; high stearic content; used in lip products and bar formulations |
Waxes: Structure, Function, and Selection
Waxes serve a different function in cosmetic formulation than oils and butters. They are used primarily to provide structure and hardness to solid products (balms, sticks, bars), to create a protective occlusive film on the skin surface, and to modify the rheology of emulsions and anhydrous formulas.
Beeswax (Cera Alba) is the most widely used wax in cosmetic formulation. It has a melting point of approximately 62–65°C, provides excellent structure and hardness, and is compatible with most cosmetic ingredients. It is used at 5–30% in lip balms and body butters, and at 1–5% in emulsions as a co-emulsifier and thickener.
Candelilla Wax is a plant-derived alternative to beeswax with a higher melting point (68–73°C) and a harder texture. It is used in vegan formulations as a beeswax substitute, typically at 50–60% of the beeswax quantity due to its higher hardness.
Carnauba Wax has the highest melting point of the commonly used cosmetic waxes (82–86°C) and is used in small amounts (0.5–2%) to increase the hardness and gloss of lip products and mascara formulations.
The Substitution Guide: How to Swap Lipids Without Ruining Your Formula
Substituting one lipid for another in an existing formula is not always straightforward. The key principle is to match the fatty acid profile and physical properties of the ingredient you are replacing as closely as possible. Replacing a high-oleic oil (such as Argan) with a high-linoleic oil (such as Rosehip) will change the skin feel, absorption rate, and oxidative stability of the formula significantly. Replacing a soft butter (such as Shea) with a hard butter (such as Kokum) will change the texture and melting point of the finished product.
When substituting, consider: fatty acid profile (oleic vs linoleic vs saturated), melting point (for solid and semi-solid products), comedogenic rating (for facial formulas), and oxidative stability (for products with a long shelf life requirement).
Frequently Asked Questions
Graininess in butter-containing products is caused by polymorphic crystallisation, a process in which the fatty acid chains in the butter rearrange into a different crystal structure during cooling. It is most common in products containing cocoa butter and is triggered by rapid temperature changes during manufacturing or storage. The solution is to cool butter-containing products slowly and steadily, avoiding refrigeration during manufacture, and to temper the butter before use by melting and cooling it slowly several times.
Yes. Rosehip Oil is high in linoleic acid (approximately 35–40%) and has a dry, fast-absorbing skin feel that is well-suited to oily and combination skin. It is used at 1–5% in facial serums and lightweight moisturisers for oily skin. Its high polyunsaturated fatty acid content means it has a relatively short shelf life (approximately 6–12 months) and benefits from the addition of an antioxidant such as Vitamin E at 0.1–0.5%.
Unrefined shea butter retains its natural colour (ivory to yellow), scent, and full complement of unsaponifiable fractions, including triterpene alcohols and phytosterols. Refined shea butter has been processed to remove colour, scent, and some of the unsaponifiable fractions. For cosmetic formulation, unrefined shea butter is generally preferred for its richer skin feel and higher content of beneficial unsaponifiables, though refined shea is preferred in formulas where a neutral colour and scent are required.
Coconut oil has a comedogenic rating of 4 out of 5, which means it has a high likelihood of clogging pores in acne-prone individuals. It is not recommended as a primary oil in facial moisturisers for oily or acne-prone skin. For dry, non-acne-prone skin, it can be used at low concentrations (2–5%) as part of a balanced oil blend. Fractionated coconut oil (Caprylic/Capric Triglyceride) has a much lower comedogenic rating and is suitable for all skin types.
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Get the Oils, Butters and Waxes GuideDisclaimer: All ingredients and products referenced in this article are intended for cosmetic use only. No therapeutic, medicinal, or TGA-regulated claims are made or implied. Always conduct a patch test before use and ensure your finished formulations comply with Australian cosmetic regulations.