There are so many wonderful oils in this world.  And just about anything can be made into an oil.  I think that is why so many of us earth citizens are worried about the biodiversity lost here on earth.  To say nothing of the animals and insects we lose each year, we don’t know what the vast majority of the plants can be used for.  There are amazing discoveries and breakthroughs each year but we still don’t even know what we don’t know.  As far as the wonderful world of soap-making is concerned we have a few ideas what oils work to make the soap and what are the best essential oils for soap making.

As we know, soap starts out as a mixture of fats, oils, and lye. In the hot process (HP) method, the raw soap is cooked until the lye has been consumed, after which, scents and colors may be added. In the cold process (CP), scents and colors are generally added before the lye has been consumed, while the raw soap is highly alkaline. Scents and colors cannot be added to CP soap after the lye has been consumed because by this point the soap is solid. For this reason, CP soapmakers must either choose scents and colors that are resistant to strong alkali, or accommodate themselves to the changes that occur in non-resistant scents and colors.

The best base oils for the skin are probably coconut, palm, olive and sweet almond.  And with that alone you can make soap…with a little lye.  But why not put some essential oils in with your soap.  The best essential oils for soap making can make your handmade soaps better by adding additional properties.  Soap doesn’t just have to be for washing!

Soap you buy at Walmart or other stores is produced by several processes, but they all share the property that the soap is made from fats and oils, shredded, mixed with scents and colors, and then pressed into bars. In this respect, it is more like melt & pour (MP) or HP soap—scents and colors are not subjected to harsh alkaline conditions because they are not added until after the alkali has been consumed.

Adding Essential Oils to Handcrafted Soap

Mass manufactured “commodity” liquid “soap” is most often a detergent. Handcrafted liquid soap is a true soap produced by a Hot Process. Because the soap remains liquid, however, scents and colors may be added after the alkali has been consumed.

An essential oil with a low boiling point may suffer loss in a MP or HP soap, and this information may be found in the MSDS for the oil. Look to ensure that the temperature of an MP or HP soap is lower than the boiling points of your essential oils when they are added.

Essential oils are complex mixtures of dozens of chemical compounds. A given essential oil may contain some compounds that react with alkali, and others that do not. Lavender oil, for example, contains about 42% linalool (which does not react) and 22% linalyl acetate (which does). In fact, when linalyl acetate reacts with alkali, one of the products is linalool. Thus the scent of a CP soap made with lavender oil will smell less of linalyl acetate and more of linalool than the original EO.

Essential Oils Reacting When you Make the Soap

The only way to predict which essential oils will react with alkali is to examine the list of components and note which of them are reactive. Such compounds generally consist of esters, phenols, and acids. There is a practical way, however, for a soapmaker to evaluate essential oil reactivity. Add a few drops of essential oil to 1 mL of the lye solution used for soapmaking (typically 25%-50% NaOH). Sometimes a reaction will be visible and sometimes not. In either case, wait a day or two and then compare the scent of the alkaline EO to that of the original. In some cases, there will be no difference in scent. In those cases where the scent changes, the alkaline scent might not be bad, just different from the original.

Phenols and acids react directly with alkali to produce odorless salts. Clove oil for example, contains a large proportion of eugenol (a phenol). If you add a few drops of clove oil to lye as described above, the resulting solution is bright yellow and very nearly odorless. Esters, on the other hand, are decomposed by lye into an acid salt (usually odorless) and an alcohol, which is often fragrant. In fact, the alcohol produced is often present as one of the components of the original EO. The scent of such an EO changes as the proportions of its components change, but it remains fragrant.

And just because an essential oil is affected by lye doesn’t mean you can’t use it; it just means that it will smell different in soap than in the bottle.

List of the Best Essential Oils in Soap Making

Peppermint- If you don’t have this in your arsenal then you may need to rethink what an essential oil is.  Peppermint has a calming effect and gives a cooling sensation to the skin (especially for me on my scalp).  This oil is a natural antibiotic and is used for probably more than this article can properly list. This oil may be the absolute top one or two best essential oils for soap making.

Eucalyptus – This is one of the more recognizable oils out there.  Eucalyptus is used for treating common ailments like the flu, colds, congestion, etc. Very good for the respiratory system.  Makes a very hygienic soap!

Majestic Pure Lavender Essential Oil, Therapeutic Grade, 4 fl. Oz
An absolute classic and the oil that I think of when I hear the term “essential oil”.  It reduces stress, promotes a calm feeling, and when in soap will clear your head.  In short, lavender will put you to sleep!

Ginger Root – Just because you have heard of it and use it in some cooking doesn’t mean it doesn’t make a great essential oil.  There have been wars fought over ginger (probably).  Two thousand years of eastern medicine can’t be completely wrong right?  Apart from being seen as an aphrodisiac it can help with pregnancy sickness and stiff joints.

Blood Orange – This is a fun one because it is basically the opposite of peppermint.  It is uplifting and more of a stimulant.  The oil is also thought to have anti-depressant properties.

Pine Needle – This one isn’t normally thought as as one of the best essential oils for soap making.  But it should be!  I pick this one because it is the smell of nature.  I can’t prove it, but I’m pretty sure pine will cure what ails you.  You do want to be careful to not use too much of this oil in your soaps.  It can be slightly irritating on the skin.  But luckily a little goes a long way.

Lemongrass – Last but not least is the invigorating lemongrass.  I personally think this is my favorite smelling essential oil.  I’m not convinced on any of its medicinal properties but I sure do love the way it smell!

So that is my short list of the best essential oils for soap making.  There are many more oils and each one should be used in its own place.  You should experiment with a few of the above and come up with your own recipes.  Soap making is more of an art than a science.  And what smell like a rose to one can seem like a skunk to another.

Essential Oil Table

The Table below is a rough guide to the boiling points of some commonly-used oils, and whether or not they are likely to be chemically changed through contact with alaki. Boiling points were taken from online sources, and I cannot vouch for accuracy. In some cases, I could not find any information on boiling points. The constituent information is mine. It is representative of a typical essential oil, but there is always natural variation. Don’t confuse Low, Middle, High with the Top, Middle and Base classification used in perfumery! In this Table, “High” means high boiling point, which correlates with low evaporation rate. Conversely, a “Low” boiling point means that it evaporates readily – a “top” note in perfumery. “Reactive?” means “is the essential oil likely to react with alkali”. The greater the percentage of acids esters or phenols, the more of the oil will be changed. But remember, the oil may still be fragrant, and actually it may still be therapeutic too. (Note that very few essential oils contain significant amounts of carboxylic acids, and these are weak acids which are not corrosive.)

Oils for soap Table