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What You Need to Know About Using Essential Oils When You Make Soap

soap science and info

Every week or so, I receive an email with a question about using essential oils in soapmaking and it's high time I round them up into a blog post for the whole Modern Soapmaking tribe! (Don't miss my other posts about essential oils.) Below, I answer common questions about using essential oils in soapmaking, including how to anchor essential oils, if they "flash off," if essential oils discolor, and so much more. Let's dive in:

Common Questions (& The Answers) About Using Essential Oils in Soapmaking

How do I anchor the aroma or get the scent to stick when using essential oils in soapmaking?

I'm a no-nonsense kind of soapmaker, and don't believe in complicating a soap formula to fix an issue, such as scent fading. If I experience a problem with a soap formula, I go back to basics and evaluate the base oils, lye solution strength, colorants, and fragrances (essential oils or fragrance oils) used.

Using particular base oils can affect the final scent of cold process soap. Natural (or non-deodorized) butters, such as shea butter and cocoa butter, can heavily affect the fragrance in cold process soap. Before "officially" going palm-free with my soapmaking, I never really used palm oil in formulating because it seemed to affect the scent as well. (I never had problems using palm kernel oil, however.) Other oils have a strong scent of their own, such as neem oil, which also needs to be considered when choosing to use essential oils in soapmaking.

Additionally, I always use well-rounded essential oil blends in soapmaking, ensuring that a blend is "anchored" with middle and base notes rather than leaving flighty top notes on their own. When using citrus essential oils, I usually opt for folded essential oils and synergize an essential oil blend with litsea cubeba (may chang) essential oil or lemongrass essential oil. Lavender essential oil is another that tends to fade on its own in soapmaking, and I tend to pair it with a small amount of another base note, such as patchouli essential oil. Other essential oils that I use to "anchor" include anise, basil, cedarwood, cinnamon, clove, oakmoss, peru balsam, and vetiver. (Some of these essential oils are not cost-effective in soapmaking for production/sale.)

 Lots and lots of citrus scented soap made with essential oils, using litsea cubeba to help anchor the citrus

While I personally do not use these methods, some soapmakers choose to add fixatives to their formulas to help anchor essential oils in soapmaking. Some of the common recommendations I've seen are mixing the essential oils into a small amount of arrowroot, cornstarch, clays, benzoin, oatmeal, or orris root powder.  I do not recommend using benzoin or orris root as both are skin sensitizers and have potential to induce allergic reactions. If you choose to use either, please label your soap accordingly.

(Want to dive deep and learn everything about using essential oils in soap and cosmetics in one place? Well, I wrote the book on that! Snag your copy of Smellgoods: How to Use & Blend Essential Oils in Handmade Soap & Skincare.)

Do essential oils "flash off" in soapmaking?

A common misconception when using essential oils in soapmaking is that an essential oil’s flashpoint in the temperature at which an essential oil will disappear or "flash off" in cold process soapmaking.

I've been known to dig into a loaf of soap during gel phase in soapmaking classes I've taught to show students the consistency of soap during gel phase (similar to petroleum jelly) as well as its temperature. (Never done it before? Use a spoon or spatula to crack into a loaf during gel phase and check it out!) It is extremely easy for the internal temperature of cold process soap during the gel phase to reach 160° F, 180° F, and even 200° F or higher. Many common essential oils have a lower flashpoint (less than 200° F.) If the flashpoint did denote a temperature at which the essential oil dissipated in soapmaking, most essential oils would not work in cold process soap making at all.

For example, Eucalyptus Globulus essential oil has a flashpoint of 118° F to 120° F. Many soapmakers start their soapmaking process at 110° F. When adding the base oils and lye solution together, it's common to see a slight rise in temperature of around ten degrees. So, eucalyptus essential oil should be just as flighty as citrus essential oils! But if you have ever made soap with eucalyptus, you know just how strong the scent is! ;)

In reality, a flashpoint is a temperature determined for the safety of transport and storage of an essential oil. The flashpoint actually denotes the temperature at which the essential oil's vapor will ignite in air when exposed to an open flame.

A more reliable temperature is the boiling point, which should be available on the essential oil’s Safety Data Sheet (SDS). (You will occasionally still see this called a Material Safety Data Sheet or MSDS. It's the same document.) Most essential oils have a boiling point above 300° F.

So, why do essential oils seem to change or fade in soap making? Some components of essential oils saponify or alter during saponification, which can change the scent of the essential oil. Most essential oils continue to evaporate as the soap cures, too. (Using a bar of soap which has faded usually revives the scent as the outer layer is washed away!) This fabulous interview between Robert Tisserand and Kevin Dunn has more information about the saponifiable content of some essential oils and how they react in soapmaking.

How much essential oil should I use for scenting soap?

There is absolutely no blanket answer for how much essential oil to use in soapmaking. It depends on the method of the process (cold process, hot process, melt and pour, etc.) as well as the essential oil itself. I've put together a small guide for calculating the usage rate of essential oils in soapmaking that you can find here. I've also created the EOCalc, our essential oil blend library and usage rate calculator.

Should I expect discoloration when using essential oils in soapmaking?

Essential oils don't tend to have as many issues with discoloration as fragrance oils do, but it can and does happen!

Folded orange essential oil can give soap a light yellow to peach hue, while dark patchouli essential oil can lend a yellow or pale tan color to cold process soap.

A good way to determine if an essential oil will affect the color of the soap itself is to look at the color of the essential oil! If an essential oil is darker than a pale to medium yellow, you can usually expect a minimal amount of discoloration. That being said, it's very rare to see discoloration to the extent of fragrance oils that contain vanilla (dark, dark brown.)

How can I get a vanilla, almond, chocolate, or coffee scent using essential oils in soapmaking?

Another common misconception about using essential oils in soapmaking is that it's not possible to mimic a lot of fragrances out there. While you won't find cucumber or banana essential oils (because they don't exist), you can create essential oil blends to evoke a wide variety of scents with a lot of practice.

Cold process soap made with coffee absolute

You can create blends with notes of vanilla, almond, and coffee using essential oils, absolutes, and CO2 extracts, but they aren't very cost effective options if you are looking to sell your creations at a low price. You absolutely will have to charge a premium for these scents, but they are oh-so worth it!

For vanilla:

  • Vanilla oleoresin can lend a somewhat balsamic and resinous vanilla note to a blend. (It does discolor in soapmaking.)
  • Peru Balsam essential oil can also be used to bring a lightly spiced but warm vanilla note to a blend. (Peru balsam should be used in extremely low amounts, and be labeled appropriately as it is a skin sensitizer.)

For almond:

  • Bitter almond essential oil can be found at a few suppliers (Rainbow Meadow carries it), but due to DEA regulations, it must be diluted with a carrier oil. Even though it is diluted, no adjustments to usage rates should be made (aka you should not use double the essential oil because it is diluted.)

For chocolate:

  • Using natural cocoa butter in soapmaking definitely pulls a chocolate-y scent through. I can usually detect cocoa butter in a recipe in as little as 5% of the formula, but most soapmakers tend to report a scent around 15% to 30%.
  • I like to use a little aged dark patchouli essential oil and peru balsam essential oil to scent cocoa butter soap to support the chocolate scent. (Add in a dash of orange or peppermint for a truly delish concoction!) Cocoa absolute is available, and does hold in a blend in soapmaking for awhile. However, it is extremely expensive and not likely something you will want to use.
  • You can also use melted bittersweet baking chocolate, but the soap will discolor a dark brown and may have brown lather depending on the amount used.

For coffee:

  • Coffee bean absolute (Coffea arabica) can be used in soapmaking for a freshly roasted coffee fragrance. Pairing the absolute with triple-brewed coffee as a water replacement and natural (non-deodorized) cocoa butter helps to push and round out the coffee scent. (Coffee absolute is solvent extracted, so it may not fit your definition of "natural" and it's extremely expensive. Though, I have to say, it's completely worth it to make a batch for yourself, if you're a coffee fan!)

Can I use floral waxes or resins with essentials oil in soapmaking?

Of course! The downside with floral waxes and resins is that you will need to soap at a higher temperature to fully incorporate the waxes and resins. I recommend melting them in a small amount of your base oils, and then adding them to the entire (hot) batch of oils. The temperatures required depends on the melting point of the waxes and resins you wish to use. You will also need to ensure that once your soap is in the mold, it is elevated and has plenty of air circulation to prevent it from overheating.

 Cold process soap made with essential oils and floral waxes (as well as natural colorants, alkanet and madder)

Last year, I made a soap using floral waxes (jasmine sambac & jasmine grandiflorum) with a blend of oakmoss, vetiver, patchouli, and ylang-ylang for family and friends, and it was a huge hit! Floral waxes are great alternative to obtaining expensive floral fragrances in soapmaking without deferring to fragrance oils. Start with a usage rate of 3% of your base oils, and make sure to help support the fragrance with other essential oils.

Do the beneficial properties of essential oils remain after saponification?

The efficacy of essential oils and their beneficial properties isn't as widely known or accepted by the medical community as a whole, and as a girl of science, I rely on scientific evidence to support my opinions. Common essential oils such as lavender and tea tree have plenty of research backing them, but other lesser known essential oils have fewer studies available. While I do love essential oils and have done a ton of research, I am, by no means, an expert and always defer to the experts! ;)

In the comments of the previously mentioned interview between Robert Tisserand and Kevin Dunn, Robert responded to a similar question with the following:

"I am not aware of any peer-reviewed studies that directly compare soap without essential oil to the same soap with essential oil, in terms of antibacterial or any other properties. But, there is plenty of anecdotal evidence that essential oils in soap are active. The heat may cause some loss of essential oil molecules through evaporation, but it should not cause any significant chemical changes." - Robert Tisserand, source of quote

While I do formulate with essential oil properties in mind, I don't rely on the purported benefits and do not perpetuate medical claims on any product I make nor the recipes I publish here on Modern Soapmaking, in accordance with FDA regulations. I always recommend soapmakers follow the established regulations in their locale, so keep that in mind!

There is so much noise and misinformation out there about essential oils! I hope this article and the resources I've shared help make using essential oils in soap making more accessible and safe for our Modern Soapmaking tribe.

Did I miss any questions you have about using essential oils in soapmaking? Leave a comment and let me know!

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