Scenting Soap with Essential Oils

scenting soap

There’s lots of science and math involved in soapmaking, and because they’re crucial to the basics of soap, science and math get most of the attention. After all, if you don’t have the right percentages of lye and fat, you won’t have soap at all, or if you do, it could be soap that’s painful to use or simply dissolves into goo when it gets wet. Like cooking, though, in soapmaking there is science and there is art. The best soap, like the best food, is combination of both.

We’ve been where you are. We’ve found ourselves wondering how to get the scent just right when starting with our unscented liquid soap.

It helps if you have a background in soapmaking, but if your background is in bar soap, you’ll discover the blend specifics aren’t the same. It also helps to remember that liquid soap is simply different from bar soap, and it’s different in enough ways that approaching it the same as bar soap will wind up wasting you time, whether through missteps or wrong assumptions. It’s good to approach liquid soap scenting as if you don’t already know everything you need to know.

Why We’re Here

Here’s the good news. Since we have been where you are, and since we kept at the scenting tests until we got it right, you can benefit from our experience. Bear in mind, as with bar soaps, that essential oils don’t all behave the same, as individual scent components or as part of a mix. The numbers that follow are presented as percentages of total soap weight.

How Art Figures into Soapmaking

There are some obvious ways in which soapmaking can be artistic and creative, choosing colors and scent blends, and — especially with melt-and-pour and small-batch traditional soapmaking — choosing swirls or sculptured tops or fun floating objects.

There are subtler forms of artistry as well, most of which are a result of experience rather than recipes or instructions. Scenting soap with essential oils, and scenting liquid Castile specifically, is one of those activities where artistry takes a subtler form.

First, the Basics

Because it’s soap, there are always numbers to begin withIf you search online for the quantity of essential oils to use in your liquid soap, you’ll find a number of sources that recommend 1% in the overall mix. One percent translates to one gram of oil to 100 grams of liquid soap base, or unscented Castile. It also translates to just over one ounce of essential oils to a gallon of soap.

This is where the art comes in. Intensity of scent is very much a personal preference, but it’s a preference based on experience — having worked with essential oils and knowing how they interact with each other.

If you have a background in bar soap, you have an advantage in scenting liquid soap. Bar soap isn’t exactly the same as liquid, but the experience will certainly help. If you’re new to soap in general, the key is experimentation and testing. You can buy a gallon, for example, and split it into fourths or eighths; as long as you scale down the oil quantities, do as many as eight different tests. Getting better can happen pretty quickly.

Some Finer Points


Here are some things to keep in mind when testing and scenting:

  • Not all essential oils are equal in how they impart scent to liquid soap and how they interact with other essential oils. It takes far less clove essential oil, for instance, than orange to reach the same scent level. Clove oil is, by nature, a stronger scent.
  • Certain essential oils are included in a blend for how they interact with other oils as much as for their own scent. Check out tea tree bars online or on the shelves. Most of them – including ours – include orange essential oil, which is there for how it takes the medicinal edge off tea tree oil as much as for its own citrus scent.
  • More isn’t always more. There’s a point in scenting soap where adding more essential oils doesn’t result in more scent — a saturation point of sorts. While we recommend one to three ounces per gallon of Castile soap, we also recommend not going beyond three ounces, regardless of how many oils you’re using. This comes up often in our custom division. There’s no point spending money on essential oils that aren’t going to add any scent.
  • For the actual mixing (whether it’s scenting or thickening), we recommend you heat your Castile to around 120 degrees Fahrenheit. The other piece of advice is to have a good immersion or stick blender and follow the most basic and conventional of wisdom: you can never stir soap too much.

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