Herbal infusions are an easy way to obtain some of the properties of a plant material for use in products. They can be used in soaps, but there is debate about whether or not the properties of the infused oils remain intact during the saponification process. Oil infusions are recommended for use in massage and bath oils, lotions, creams, scrubs and balms. Basically, any product that contains oil can use an infused oil in its place. There are several methods to infuse herbs in oils.
Fresh herbs in hot oil - This method is perfect if you have access to fresh herbs. It’s also great from a marketing standpoint if you can tell your customers that your products are infused with herbs fresh from your very own garden or from a local farm. You’ll want to gather the herbs early in the day and allow them to wilt to remove excess moisture before infusing them.
The crock pot works best for hot oil infusions, unless you can obtain a heat diffusing mat or simmer mat. These mats can be purchased online or in kitchen stores that carry specialty products. Stove top temperatures are too high for proper infusions and will cook your herbs, depleting them of their properties.
Place your herbs in the pot. Add enough oil to just cover the herbs. As a starting point, try 1 part fresh herbs to 1 part of oil. Allow to heat at a temperature of 120-130 degrees. The “warm” setting on the crock pot should achieve this temperature, but as brands vary, you’ll need a thermometer to be safe until you’re sure of your crock pot’s settings. Remember, we do not want to cook the herbs. Simmer at this temperature for 2 - 3 hours. Once the oil has cooled, strain the herbs out of the oil using a couple layers of cheesecloth, which can be purchased at kitchen or craft stores. You can then use the infused oil in place of any oil in your recipe.
Dried herbs in hot oil – If you don’t have a green thumb or simply lack the time and patience to grow your own herbs, fear not. Dried herbs work well, too, and still contain much of the therapeutic properties of the plant. Dried herbs can be purchased from a host of companies, including soap suppliers. Simply follow the instructions for the fresh herbs listed in the paragraph above, but use 1 part of dried herbs to 2 parts of oil.
Dried herbs in “cold” oil – The cold infusion method is one of my personal favorites. It involves steeping the herbs and oils in the sun, which results in lovely jars full of infusions on the windowsills. The drawback to this method is that it takes weeks, and you cannot use fresh herbs, since their water content does not evaporate in a jar. But you can dry your herbs and then use the cold infusion method.
Sterilize a mason jar, or something similar. This can be accomplished by placing the jar in boiling water or by running it through the “antibacterial” cycle on your dishwasher. If you have ever canned food before, you will be very familiar with this important first step. You can either pack your jar with herbs and then pour the oil over the top or, for smaller recipes, use 1 part herbs to 2 parts of oil. Seal the jar tightly with a clean lid. Place the jar on a windowsill with lots of sun for 3 - 4 weeks. Give the jar a quick shake once daily. The object is to keep the jar warm as the herbs steep in the oils, so if you live in a cold climate, take that into consideration.
Further information on infusions – The choice of oils to use is entirely up to you. Choose the oils based on the benefits you would like to achieve. You may also use a combination of oils. If you are looking for a stronger infusion, simply repeat any of the processes above, adding new herbs after you have strained the old ones. If using the infused oils in something other than soap, it is recommended that you add vitamin E to slow the oxidation in the oils. It will extend the shelf life of your infusion and prevent the oils from going rancid too quickly.