Herbal Oils

Fat is the medium for most external herbal medicine. ‘Fat’ = lipids, and the kinds of fat we use in medicine making are mixtures of triglycerides (similar to what we find in body fat, animal fats, and what we’ll be speaking most about here: plant-based oils).

Fat absorbs the fat-soluble medicinal constituents of plants so we can apply them to our skin. Whether the carrier is an animal-based fat (like tallow, which is a rendered form of beef fat), or plant-based oils (olive oil, sunflower oil, and many others), these fats suspend and carry the properties of plants to the largest organ that connects us to the outside world.

In addition to absorbing and carrying the medicinal properties of certain plants, fat provides a soothing and nutrient-dense meal to the skin alongside whatever plant properties were infused into it.

Infused oils shine in the realms of massage therapy, wound healing, lymph and circulatory support, soothing sore muscles and joints, anti-spasmodic relief, and moistening dry skin.

I tend to use dried herbs when making infused oils as it reduces the possibility of an oil going rancid, but there are some instances where a fresh herb may be used with some care.

What carrier oil should I use?

I use this term ‘carrier oil’ to refer simply to the kind of oil that will be ‘carrying’ the medicinal properties of the plant you infuse into it. Most herbalists stick with olive oil because it’s widely available and relatively inexpensive, although some say it clogs pores. I tend to use sunflower oil because it has high levels of vitamin E which support shelf stability, it doesn’t clog pores, and I have a really high-quality and relatively local source of a sunflower oil that I love.

There are many many other oils, and honestly the place I go to learn more about an oil I'm not familiar with is Mountain Rose Herb’s carrier oil products page where they offer up information on oils from Jojoba, Apricot Kernel Oil, Sea Buckthorn Oil, and many others. This is a rabbit hole you might want to go down if you’re more interested in cosmetics, topicals and massage oils, but for most purposes sunflower oil and olive oil will do the trick.

How to make an herbal oil:

There are many methods for crafting an herbal oil, but I will cover the two I primarily use. The first resembles making a tincture and the second is like making a low-heat decoction. You can also combine the two, as I often do. An infused oil is also the first step in making a salve.

Cold Extraction Method

Throw finely chopped or powdered dried herbs into a glass jar. Add enough oil to barely cover the plant material (if you want to use a ratio, I tend to use ratios of between 1:4 - 1:6… similar to that of making a tincture). You can also combine the dried herb and oil in a blender and blitz for a minute or two to expose more surface area of the herb. Store the jar in a warm area for 3-6 weeks, shaking every so often, then strain, press, and bottle the oil.

Warmth aids in the process of extracting the herbs into the oil, so if it’s winter I will often put my infusing oil close to my radiator, and in the summer I might infuse it in my hot car. Too much heat can mess with the oil though, so there is a balance that needs to be found.

A lot of people like to ‘Solar Infuse’ their oils. While I don’t typically do this for tinctures, I do often do this for St. John's Wort in particular. However, it’s important to store herbs at all other times out of direct sunlight which can degrade the herbs more quickly.

Gentle Heat / Stovetop Method

In this method, we rely on gentle heat to ‘quickly’ infuse our oil. To use this method you will need a double boiler (or the ability to rig one up with a stainless steel or pyrex bowl and a saucepan/pot of sorts).

In the pot, add a few inches of water with space between the double boiler and the surface of the water. It’s important that the water be replenished as it evaporates off over time. Heat to around 120 - 130ºF (also helps to have a thermometer). Make sure the oil never boils, and even going above 140ºF can compromise the integrity of the oil and cause it to go rancid more quickly after preparation. Go slow and low, at least 4 hours infusing at this temperature. Make sure to not cover the oil to avoid condensation falling into your oil infusion. Stir frequently throughout (I often find that the oil at the bottom is significantly hotter than the oil on top, so stirring every once in a while keeps an even distribution of heat throughout the oil.

You could call it quits at four hours or keep going for a stronger infusion. Once I’m done for the night, I like to cut the flame, remove the double boiler, and then cover the oil and leave overnight for extra infusion and then strain the following day. You could also restart the infusion the following day, repeating for as many days as desired (although more than a week is probably overkill).

How to make an herbal infused oil using the stovetop method:

1. Weigh out 100g of herb and 400 ml of sunflower oil (for a 1:4 ratio).
2. If using fresh herb, prepare the herb using one of the two methods below.
   1. Mortar and Pestle: crush the herbs in a tablespoon or so of the oil (just enough to make the process easier) and then transfer to your glass jar.
   2. Pruners & Blender: use garden pruners to cut the herbs into small enough pieces so it can fit in a blender.
3. Combine in a blender and blitz for a few seconds to break down the plant material and incorporate into the oil.
4. Transfer to a double boiler and gently heat via the stovetop method from 2pm - 8pm.
5. Cut heat, remove double boiler, cover and allow to continue infusing on the ambient heat of the stove overnight.
6. (Optional) Transfer to a jar and allow to infuse another week or two (via the cold extraction method).
7. Strain/press, bottle, and label.
   1. If you started with fresh herbs, you might want to avoid pressing the oil as this will further press out any water that was still present in the plant material into the oil (which may cause the finished oil to mold) – just let gravity do it's thing when straining!
      1. You might also want to let the oil stand for a day or two (or up to a week if you want to be really sure) to allow the oil to separate from any remaining water (oil sits on top of water so you will notice a separation after a few days).
      2. Carefully pour off the oil, leaving the remaining water behind and store in an opaque bottle – you can also use an auto-siphon to more easily decant the oil and leave the sludgy oily water behind in the jar.

Many herbalists say this method can yield a high quality infused oil in as little as four hours. I like to heat my oils for around 3-5 days, which is easy since I have a lab-grade hotplate that I don’t have to constantly monitor. This might be a little more challenging on a stovetop with open flames, but like I mentioned above, if you want a longer infusion, you can just pause overnight and restart the following day (it will continue infusing off the heat, just a little slower).

Now you’ve made your infused oil and are ready to turn it into a salve! But first, I want to share a couple other notes and nuances around the process of making infused oils, first up:

Things that ruins oils after you’ve made them:

• Little particles of plant material (provides a medium for things to grow on)
  • This really shouldn’t be an issue if you plan on using the oil soon after you make it, but if you plan for longer term storage, or are selling commercially, you might want to consider using a paper filter (for obvious reasons–see below if not so obvious–do not rinse the filter with water before straining oil through it).
• There can be residual water from fresh plants in your oil (which also provides media for weird stuff to grow on).
• Oils will start to oxidize some time after you prepare them (the time at which an oil oxidizes depends on the kind of oils you are using, some are more shelf stable than others).

How you can increase shelf stability:

• Adding Vitamin E oil acts as a preservative and slows down the oil oxidation process or prevents rancidity. This step, however, does not compensate for water or plant material in your oil.
• Using paper filters (except for Kava Kava oil, which will not strain through paper filters).
• If using fresh herbs, after you’ve infused the oil, let it sit on the counter undisturbed for a week, wherein all residual water settles to the bottom (since oil floats on water), and you can decant (i.e. slowly pour off) the crystal clear oil without getting the water/sludge in the pure infused oil.
  • This can be hard, and frustrating, you might leave some oil behind and that’s okay, better than spoiling your entire batch!
  • Perhaps the ‘sludge’ oil is the herbalist’s share… the oil you use for yourself since you can handle the sludge and know you will use it before it goes ‘off’.

Lastly, oil degrades latex, so you can’t use rubber latex dropper caps to store infused oils. If you need a dropper, purchase ‘monprene’ droppers which do not react to oils (monprene droppers also do not allow tinctures to extract the rubber into them, which is why I’ve switched to using exclusively monprene droppers).

Intermediate Solvents

You can also use intermediate solvents to make a more potent oil. Here you would moisten your plant material first in high-proof alcohol:

Measure the amount of plant material by weight, powder, and add 50-75% of that weight in 95% alcohol to the plant material and let sit for 4-12 hours (I often do this in the vessel I will infuse in).

For example if starting with 100g of plantain leaf, you would powder, or blend the plantain leaf in a vitamix, then add 50-75ml of 95% alcohol and stir to ensure the powdered herbs are evenly coated in the small amount of alcohol. The amount you add depends on the herb, but you are looking for a moistened sand on the beach texture. Let sit and then move on to the steps above to create your infused oil.

I almost always use intermediate solvents for my infused oils, and they seem to come out more potent and with more color.

…okay NOW you are ready to make a salve.