In one of your comments, you advised that some essential oils saponify in cold process soap making. Do you by chance happen to have access to any studies that show this? I’ve gone through Kevin Dunn’s Scientific Soapmaking and I’ve yet to encounter an essential oil that actually saponifies when lye is added to them directly. My brain can’t wrap around the possibility of saponification of essential oils as they are not lipid oils. That’s not to say that it can’t happen, as I’ve only tested personally the essentials I have on hand. Which is not a complete list by any means.
Any research you have come across that addresses this would be greatly appreciated.
Thank you for your time.
Kris Boggs -- K.B.
Thanks for the note! It was a published interview between Kevin Dunn and Robert Tisserand and can be found online. Also in a personal conversation, I had with Kevin he pointed out that a form of saponification was possible and gave the example of the Linalool in Lavender being converted into linalyl acetate, which is the more fragrant compound. So essentials oils can undergo a "change". Saponification is also possible because some essential oils do actually contain plant "FATS", they are not entirely aromatics. Kevin did not cite any specific research studies on it. Tisserand states that little research has gone into how essential oils react in anything. For example, we don't know how they react when mixed with synthetic fragrances, because there has not been any definitive research on that topic. Scientists" are more interested in "constituents" because focusing on one ingredient is far less expensive to research. Constituents that have health benefits are of interest to the medical community. Sadly, Tisserand is one of the few reliable sources for essential oil research, but he has focused on therapuetic applications and not soap. That was part of the reason for the interview between them. Kevin spent more time directly on soap.
So to put it simply, any plant "fats" in the essential oils can saponify, but that does not mean 100% of the essential oil will saponify. Make sense?
Hope this helps!
I have struggled with Lemongrass EO in cold process soap - often batches are spotty (DOS). I have tried soaping at lower temps. I have changed formulation -- and still having issues. Is there a particular fixed oil that could be interacting with the Lemongrass? Other recommendations you could offer (besides discontinuing the soap)? Thanks in advance -- T.T.
Sorry for the delay in responding, I was out of the country for the last two weeks. I have not experienced the problem you describe with Lemongrass. A couple things to consider:
1). Is the Lemongrass batch fresh or is it aged? With aging can come oxidation and the oil does not perform well in soap once that has happened.
2). Did you get a Certificate of Analysis with the Lemongrass? Lemongrass is frequently adulterated with Citral and you can also get strange results from a high level of that.
3). Never use Lemongrass above a 5% level in your recipe.
4). A good fixative is Atlas Cedarwood and/or Balsam Pine, but of course, it will impact the true lemongrass fragrance.
As I have said I have never had an issue with Lemongrass bars having spots myself, so all that really leaves is the recipe. If you don't mind sharing your ingredients, I can take a look at that.
Hi there! Not sure if this question should go to you or not - but here goes! We are looking into making our own teas, extracts, etc from our herb garden. I have seen several cold process soap recipes that add extracts but I'm having trouble figuring out if these are alcohol based or glycerin based and which step they should be added in (although so far I've read that light trace is the time). Can you help? I can make extracts using either medium I just don't want to end up destroying a test batch or blowing up my lye because I added the wrong type at the wrong time!
Any help would be appreciated,
Michelle -- D.P.
When I make soaps with teas and plant extracts, I add them into the lye base and do not use alcohol (we avoid it whenever we can). For example, instead of plain water in with lye I will use the tea as the entire water replacement. But I steep the tea to be quite strong if I am using it in soap.
Extracts are tricky and it depends what it is how it is made. We typically do either a water or an oil infusion, simpler to work with in the soap we have found. Too much glycerin will give you rivers. I don't know if you are using goat milk or not and if so, that is where you have to watch our using too much glycerin.
The infused oil will replace all or just a portion of your oils in the recipe. Therapuetic benefit can be obtained with a lessor amount than trying to get the scent from an infusion alone.
Does this help?
I have recently started making cold process soap. Most of the research I've done on essential oils in soap state the use is 1 ounce per pound of soap, or, some calculators state the use is 3% of the total oils in the soap. My test batch recipe is 32 ounces of oil. 3% is about an ounce of EO. By the time my soap cures, there is very little scent. I use primarily USDA certified organic EOs; if not organic, then therapeutic grade. Can I use more EO so the scent will be stronger?
Mary -- M.A.
Thanks for the question. Because it is a wash-off product, essential oil safety guidelines will allow up to 5%-7% depending on which oil is used. There are some where more caution and dilution is necessary.
If you are using any of the citruses however, they have much lighter molecules and are more aromatic. Aromatic meaning high evaporation rather than more scent. You will lose the scent much faster in any citrus oil. It is a fact that we don't like, but have to respect.
Your recipe will also have an effect. If you are using any butters that are raw and still have a scent of their own (raw cocoa butter), it can mask the EO scent to some degree.
Of course, do a test to see if your EO reacts with alkali, because if it does the batch can accelerate significantly, which can challenge you even if the scent is great.
Some essential oils are simply not meant for soap, either because of cost or because of potential for irritation.
Let me know if you have any other questions!
As a general rule how long will an essential scent last in a cold process soap? Thank you! -- V.C.
I apologize for the delay. HSCG had trouble with my experts portal and I could not get into answer until now. Please forgive the delay.
How long an EO will last in cold process is dependent upon the oil used primarily. Citrus oils will lose their scent the fastest, no matter the type. Lemon, Lime, Tangerine, Bergamot....they all will fade usually within 2 - 3 months.
The less volatile the oil, the longer the scent will stay and there are some that are good for a year or more. Some that will stay are Lavender, Spearmint, Eucalyptus, Clove, Citronella, Patchouli, Cedarwood, Frankincense. But it takes at least 5% essential oil in the recipe. If you use 1 - 2% you will not have a lasting scent.
Of course the recipe you use will also affect the EO longevity. If you use heavy butters, like cocoa butter, it can mask EO to a certain degree, reducing the scent. All EO's will have a "slight" scent alteration because of the alkali reaction. Some EO's actually saponify in soap and others do not.
So it is a complex answer with many variables. But overall, with the exception of citrus, you should still be able to detect a scent at 9 months to a year in an EO soap that is made correctly.
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