How to Make an Infused Herbal Oil
Infused oils are one of the foundational preparations in herbal practice. They are the backbone of salves, balms, and body oils, and they can also be used on their own, applied directly to skin or used in massage. The process is exactly what it sounds like: you steep dried (or sometimes fresh) herbs in a carrier oil, allowing the plant's oil-soluble constituents to transfer into the oil over time.
This is different from an essential oil, which is a steam-distilled or cold-pressed concentrate requiring specialist equipment. An infused oil is something anyone can make at home with a jar, some oil, and a little patience.
Choosing Your Carrier Oil
The oil you choose matters, both for the preparation itself and for its intended use. Different oils have different shelf lives, textures, and skin affinities.
- Olive oil is traditional, deeply moisturising, and stable. It has a noticeable scent, which some people love and others find distracting. It is an excellent choice for salves and medicinal preparations.
- Fractionated coconut oil is light, odourless, and has a long shelf life. Good for skin preparations where you want a non-greasy result.
- Sweet almond oil is nourishing, mild, and well tolerated by most skin types. A good all-purpose choice for body oils.
- Jojoba is technically a liquid wax and is exceptionally stable. It closely mimics the skin's own sebum, making it excellent for facial preparations.
- Sunflower oil is lightweight, affordable, and widely available. A reliable everyday option.
The Cold (Slow) Method
This is the traditional approach, and many herbalists prefer it because gentle, unforced extraction preserves a broader range of constituents.
Method:
- Make sure your herb is fully dried. Moisture is the enemy of infused oils, causing the oil to go rancid and creating conditions for bacterial growth.
- Fill a clean, dry glass jar about halfway with your dried herb.
- Pour your carrier oil over the herb until it is completely submerged, with at least an inch of oil above the plant material.
- Seal tightly and label.
- Place in a warm, sunny windowsill or a warm spot in your home. The gentle warmth of sunlight helps draw the constituents into the oil.
- Leave for 4 to 6 weeks, shaking or turning the jar every few days.
- Strain through cheesecloth, pressing the plant material firmly to extract every drop.
- Bottle in dark glass and store away from heat and light.
The Warm (Fast) Method
When you need your oil sooner, gentle heat can compress weeks into hours.
Double boiler method: Place herb and oil in a double boiler or a heat-safe bowl set over a saucepan of water. Maintain a very gentle heat (below 65°C / 150°F) for 2 to 8 hours. Do not let it boil or simmer aggressively. Strain and bottle as above.
Slow cooker method: Place herb and oil in a slow cooker on the lowest setting (or the "warm" setting) for 4 to 8 hours with the lid slightly ajar.
The warm method sacrifices a little of the nuance of a long, slow extraction, but it produces a perfectly good oil that is ready when you need it.
A Note on Fresh Herbs
Some preparations call for fresh or wilted herbs rather than dried. Lemon balm, St John's Wort flowers, and fresh lavender are examples where herbalists sometimes prefer fresh. If you are using fresh herb, wilt it for 24 hours on a clean surface first (this allows some surface moisture to evaporate), and use the warm method rather than the cold method. Watch your oil closely for any signs of moisture or fermentation.
What to Do With Your Infused Oil
Infused oils can be used directly as a skin oil or massage oil, or they can become the base for salves, balms, creams, and lip treatments. They are also used in some culinary traditions, though culinary infused oils have different safety considerations than topical preparations.
A Note on Safety
Infused Oils are among the gentler preparation forms in herbalism, but the herbs themselves still carry their own safety considerations. Check the herb profiles in The Herbalist's Codex for any safety notes relevant to the plants you are working with.