Infusing oil with herbal material allows you to extract the constituents which can then be applied to the skin. You can infuse oil in a few hours on the stove, or leave oils to infuse naturally over a few weeks in a sunny spot. The infused oils are really versatile, they can be used directly or made into varying consistencies such as ointments, balms or salves (salves tend to be thinner and more oily, while balms are a little more waxy) for topical uses.
What type of oil you infuse with is up to you. Our ancestors would have rendered animal fat to make their ointments but thankfully, today we have quite a choice. For infusions, ideally you want a longer shelf life, low rancidity and smoke point - I most often use olive oil as I have it in stock and ticks all the boxes.
Some common oil choices include:
Olive Oil: affordable, fairly stable under heat, nourishing, low allergy risk, mild scent
Coconut oil: stable, cheap, odourless, solid at room temp, UK, so no need for beeswax
Grape seed oil: less stable (shorter shelf life), odourless, light and absorbent
Almond oil: emollient, good for dry skin, possible nut allergy, slightly more expensive
Any oil will do!
For balms and salves you can mix with:
Jojoba is a light and gentle oil, good for every day use
Rose hip: a light oil, antioxidant, anti-ageing and sensitive skin, expensive
Shea butter: nuts of the shea tree, solid at room temp (UK) anti-inflammatory, oily
Cocoa butter: can be added to solidify, made from cocoa beans, greasy, chocolate scent
Herbal Oil - Sun Method (Slow Method: Weeks)
Sterilise a suitable clear glass vessel. Wash well and drip dry. Place in the oven at 120 degrees for 20 min, or until the glass is fully dry.
Fill a sterilised glass with dried herbs, you might like to bash or chop with sterilised utensils to increase the surface area for a faster maceration. There are a few exceptions where you use fresh wilted herbs but as a rule you should dry before using or you have the potential for a science experiment with botulism…
Cover with oil, press the herbs down firmly to remove any air bubbles. Ensure the oil submerges all of the plant material otherwise you might get mould and ruin your oil. Hold down under the oil with a big leaf or glass weight, if necessary.
Seal and leave to infuse in a windowsill (not direct sunlight), turn the jar each day for 2 -5 weeks. Don't leave it too long as the oils may oxidise and the herbs will lose potency. Once the oil gains 'colour' (the constituents leeching from the plant into the oil), it will be ready.
Strain through muslin or a sieve to remove the herbal material. You can compost the herbs. You could also do a second infusion at this point.
Pour the remaining infused oil into a sterilised, dark glass bottle. Add 1% vitamin E oil and possible Essential oils (optional) to extend shelf life.
Label, date and store in a cool, dark cupboard. Can last up to a year if stored in a cool and dark cupboard, discard if the oil smells rancid.
Herbal Oil - Bain Marie (Fast method: hours)
Make a Bain Marie: pop a pan on the stove. Fill 1/4 full with water. Inside place a heat proof glass bowl which you will fill with herbs and oil. You can pop a ring in so that the bowl does not make contact with the pan and burn the herbs. Or, use a bowl big enough so that the bowl can rest on the rim of the pan and doesn’t touch the water underneath.
You can bash or chop with sterilised utensils to increase the surface area for a faster maceration.
Bring the water to the boil and then simmer. Do not allow water to make contact with the oil. Be careful not to let the pan boil dry and continue topping up with water while the herbs infuse. This can take anywhere up to 1 hour to 4 hours, or until the oil becomes coloured with the constituents.
When the oil has infused remove the bowl from the pan and strain the oil through a muslin cloth.
Place the oil into a sterilised dark glass bottle. Add vitamin E (optional). Seal, label and date. If you keep it in a dark and cool place the infused oil could last up to one year, depending on the oil used, discard if the oil smells rancid.
The shelf life of oil-based infusions varies from 6 months - 1 year. Oils oxidise easily (go rancid) and some do that faster than others. Once you have made the oil you can help to extend the shelf life by also add 1% vitamin E oil, (or rosemary oil) which is an antioxidant. Storing the oil in dark glass bottles and in a dark cool place will help too.