Macerated oils, also called infused oils, are carrier oils that have been used as a solvent to extract the therapeutic properties of a certain plant or plants. The base oils commonly used are Olive or Sunflower and the process is quite simple. Because of risk of microbiological infection caused by wet herbs infusing in oil, it is recommend to use only properly dried herbs and flowers for this process.
If you harvest the fruits, vegetables and herbs from your gardens, orchards and hedgerows each autumn, you might be jamming, pickling, drying and preserving all that beautiful produce. It is also a perfect time to make some infused herbal oils to use in your skincare formulations. And infusing, or ‘macerating’ oils with herbs is a great way of extracting many of the plant’s properties.
Many of the oils that you can buy in the shops are obtained by ‘cold pressing’ the seeds of the plant. Olive oil, sunflower oil and rosehip seed oils are all great examples. However, there are some plants that don’t contain a sufficient amount of oil to obtain it by pressing – which is where maceration comes in.
How to make a maceration
If you want to extract the therapeutic properties of a particular plant into oil then firstly, you will need a good quality fixed oil to use as a base. If you are planning to use your macerated oils for skincare, then consider olive oil, sunflower oil, sweet almond oil or even jojoba oil. If you want a thicker blend, coconut oil can be fun to experiment with too.
Secondly, you will need to harvest your plant material and make sure that it’s as dry as possible. You can use fresh plant matter, but you will need to regularly replace this in the maceration because it will contain lots of water which can turn your oil rancid and encourage microbial growth. Try to chop the plants as finely as possible, which means you will break the plant cell walls and encourage more of the plant’s oil-soluble compounds to infuse into your base oil.
Next, clean an airtight container (such as a jam jar with a tight fitting lid) and fill it with your chopped plants. Pour the oil of your choice over the top and make sure that all of the plant material is covered by the oil.
Macerating works best when done in gentle heat. The traditional way of doing this involves putting your dried plant matter and oil in an airtight container such as a glass jar and placing it in a warm sunny location for up to three weeks. The sunshine will gently heat the oil and extract many of the plant’s properties. Every week or so, replace the macerated herbs with new plant material so you can continue to extract more therapeutic properties into your base oil.
However, some people prefer not to wait that long – so macerating can also be done in a bain-marie (or double boiler) for an hour or even in a slow cooker overnight. The most important point to remember is to keep the heat as low as possible. You don’t want to overheat the oil and you don’t want to scorch the plant material.
Some oils are more vulnerable to rancidity than others – so it is a good idea to include 0.5 – 1.0% of Vitamin E oil in your maceration before you start. Vitamin E, or Tocopherol, is a powerful antioxidant and can help stop your oils from going rancid too quickly. You will know when your oil goes rancid, because it will start to smell strange and look cloudy.
Now that you’ve got your plants macerating in the base oil, remember to gently stir or shake the mixture every day. If you stir the mixture regularly then you will encourage the transfer of the oil-soluble chemicals in the plant into the maceration – and create a more potent therapeutic blend.
Once the maceration is finished, you will probably find that your base oil has taken on a new colour. You will then need to strain or filter the herbs and pour the final oil maceration into a sterilised airtight container. Make sure to label it too because you don’t want to forget what was in it and when you bottled it!
Most macerated oils will then keep for a period of 6-12 months if you store them out of direct sunlight and heat. Try to keep them in fairly small containers – so you don’t have large amounts of air in the container.
Macerated Oil Ideas
When macerating oils for skincare, consider using any of the following plants: Calendula (marigold) petals, St. John’s Wort buds and flowers, carrot root or even sea buckthorn berries. All of these plants will impart lovely rich colours to the base oil and provide great therapeutic properties in beauty products. Macerated oils can be used in your formulas at 5-10% as an ‘active botanical’ or used in larger quantity as a replacement for a plain base oil.
- Calendula is anti-inflammatory and has shown great success in healing balms (you might have noticed that some of the big supermarket brands even infuse their balm tissues with Calendula!).
- St. John’s Wort has been used historically for the topical treatment of bruises and mild burns – and to speed wound healing.
- Carrot is soothing on the skin and is thought to help with itchy skin.
- Sea Buckthorn is valued for its rejuvenating and anti-ageing properties and you can often find it in expensive shop-bought cosmetics.
Macerated oils are also made to impart beautiful fragrances into skincare products. You can, for instance, macerate vanilla pods into jojoba oil to create a beautiful vanilla-jojoba infusion.
Or you may have come across Monoi de Tahite before which is a macerated oil traditionally prepared in French Polynesia by infusing gardenia (tiare) flowers in pure coconut oil for two weeks. The flowers are picked as fresh buds and impart the most intoxicating, luxurious fragrance to the coconut oil.
So you now have your macerated oil ready for use! Oil infusions are used widely in skincare and there are many different blending options to choose from. Happy macerating!
Please note – It goes without saying that if you intend to experiment with any herbs for skincare, you should always do a skin patch test first. Although all of the ingredients mentioned in this article are natural and safe to use on the skin, some people can be allergic or sensitive to certain plants which can cause dermatitis or allergic reactions. Be sensible and always test new ingredients out before incorporating them into any kind of skincare regime.
Macerates vs Essential oils
If you’re wondering why to bother making macerated oils when we have essential oil, it is important to know that not every constituent of a plant comes over in distillation. Only the smaller molecules come over using that method and so we never quite capture the essence of the whole plant.
Maceration captures the heavier larger molecules. Other extraction techniques will capture other chemicals too—water extracts will harness the water-based compounds for example. So the more ways you have to extract the properties of a plant, the closer you get to accessing everything that plant has to offer.
When making a cream that is based on lavender, for example, then you can augment the therapeutic effect by also including macerated lavender oil and even the fluid extracts or hydrosols too.
Also you may have access to a plant that doesn’t have a corresponding essential oil, Lilac or Elderflower for example, or perhaps you wish to use a plant where the essential oil is very expensive, i.e. Jasmine (distilled) or Lemon Balm. By using maceration you can access the healing chemical compounds in these plants and use them in your skincare.
Want to make your own botanical skincare? Check out our courses and study with us to become an organic skincare formulator!
Read more about making macerated oils:
- How to choose the right botanical oil for macerations
- The 8 best oils for making botanical oil infusions
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Lorraine Dallmeier is a Biologist, Environmental Scientist and the Director of Formula Botanica, the award-winning online organic cosmetic science school. Read more about Lorraine and the Formula Botanica Team.