Castile soap is a very popular choice for personal care and cleaning. Be aware of these tips to know what to buy and to avoid low-quality brands with unnecessary and potentially toxic additives.
The first time you browse the personal care aisles of a health food store, it’s hard not to immediately notice the numerous, colorful bottles and bars of Castile soap on display.
These brands are obviously good sellers, which is why retailers allocate them prime shelf space.
Just because an item is popular and sits on the shelf of a health food store, however, doesn’t necessarily make it a healthy nor even a green choice.
Any veteran foodie or greenie knows this to be true!
So what’s the real story behind Castile soap?
Is this product truly worth your budget dollars to purchase? Is it a safe personal care item for your family to be using?
Or, is it just another product that has been twisted by manufacturers into a modern-day version of its historical self that has little resemblance chemically or otherwise to its traditional roots?
History of Castile Soap
Castile soap, pronounced “kas-teel”, is rooted in the traditions of the Eastern Mediterranean where Aleppo soap makers made hard cleansing bars out of laurel oil and lye.
Laurel oil is derived from the aromatic Laurus nobilis, an evergreen tree or large shrub with green, glossy leaves and is native to Syria.
To this day, the origins of Aleppo soap remain unclear. Claims that the Egyptian Queen Cleopatra and Queen Zenobia of Syria used Aleppo soap abound but have yet to be verified.
As of this writing, we only know for sure that this important precursor to Castile soap cleansed the skin and hair of humankind for millennia.
The common belief is that the Crusaders brought Aleppo soap back to Europe with them during the 11th century.
Since laurel oil was not available in this part of the world, it was replaced with olive oil in the Castile region of Spain.
Castile soap was born!
Castile soap is known today as any vegetable oil-based soap. This distinguishes it from soaps made with animal fat such as tallow, lard, or goat milk.
Hence, the Castile soaps of today are commonly made with olive oil, coconut oil, palm oil, and others.
Castile Soap-Making
Traditional Castile soap is made by blending olive oil and lye. Lye, also called caustic soda, is the common name for sodium hydroxide or potassium hydroxide. Both are highly alkaline, liquid compounds.
They are also very caustic. Food grade lye is used to cure a wide variety of foods with lower grades of lye used in drain de-cloggers and oven cleaners.
Both the sodium hydroxide and potassium hydroxide forms of lye are used in making soap. Sodium hydroxide is favored for making solid Castile soap with potassium hydroxide used for liquid soaps.
They are not interchangeable, however. Potassium hydroxide-derived Castile soaps are more easily dissolved and diluted in water and are hence favored for liquid soap production for this reason.
The typical cold process method for making Castile soap is as follows:
- Lye is mixed with water.
- Vegetable oils and fragrances blended into the lye mixture.
- The gradual chemical reaction between the lye and the fats produces a solid soap as the mixture ages or “cures” over a period of several months.
While the cold process method is very straightforward, the hot process method for making Castile soap is actually far more popular.
It significantly reduces cure time from months to a few weeks and requires a smaller amount of essential oils to scent.
Hot process Castile soap is made using either the stovetop, a crockpot, or even in the oven. Only olive oil, distilled water, and lye are needed. (1)
Commercial Brands
Due to the long curing time required to make traditional castile soap, consumers have flocked to commercial preparations.
The good news is that some truly traditional, green Castile soaps are available. The bad news is that consumers would do well to avoid some brands that include unnecessary, even toxic, additives.
What should you look for as an educated consumer?
First of all, the old rule of thumb “the fewer ingredients the better” definitely applies to Castile-based soaps. Ideally, a liquid or bar should contain just three ingredients: oil, distilled water, and lye (either potassium or sodium hydroxide).
All of these ingredients are considered safe, certainly in the dilute amounts found in Castile soap.
Even at full strength, the Environmental Working Group (EWG) identifies lye as a low health risk with skin, eye, or lung irritation possible only when precautions are not taken. (2)
This is why rubber gloves and protective eyewear is necessary when making Castile soap yourself at home.
As a result, buying Castile soap either in bar or liquid form from the store is definitely a green choice when the manufacturers use just a few simple ingredients.
Which Oil is Best?
Olive oil is the most traditional oil for authentic Castile soap. However, any healthy fat will do the job. Coconut oil and palm oil are other excellent choices from when sustainable sources that are ideally organic.
Avoid soy or canola-based Castile soap as these are likely GMO unless certified organic.
A GMO-based soap would likely contain pesticide residues and be an unsustainable choice from an environmental point of view.
Watch out for Toxic Additives
Additional ingredients beyond the three basic ones described above are not necessarily a problem.
As a savvy consumer, be sure to read Castile soap labels and be aware that some non-green, unhealthy additives are possible that you need to watch out for.
Some common additives to commercial brands of Castile soap include:
- Fragrance
- Citric acid
- Glycerin
- Ethanol
- Calcium Carbonate
- Tocopherol (Vitamin E)
- Menthol
- Xanthan gum
- Potassium Cocoate
- Baking soda
- Silica
- Sodium Chloride (salt)
- Variety of essential oils and herbal extracts
The three ingredients marked in red above are the ones that are cause for concern.
Glycerin and citric acid, while generally nontoxic according to the EWG Skin Deep database, could be of GMO origin (either corn for citric acid or soy oil for glycerin). Be sure to check with the manufacturer of the Castile soap brand you prefer to be sure of nonGMO ingredients.
The ingredient with the biggest risk in Castile soap is fragrance. It has as a high hazard (8 on a scale of 10) by EWG. Castile soap or any personal care product that contains it has these health risks:
The word “fragrance” or “parfum” on the product label represents an undisclosed mixture of various scent chemicals and ingredients used as fragrance dispersants such as diethyl phthalate. Fragrance mixes have been associated with allergies, dermatitis, respiratory distress and potential effects on the reproductive system. (3)
Safest Ingredients
In sum, if you purchase Castile soap in either liquid or bar form, ensure that the label lists only basic ingredients such as nonGMO vegetable oil(s), distilled water, and lye (such as this brand).
A natural preservative such as tocopherol (Vitamin E) is fine too.
If you really prefer scented versions of Castile soap, be sure to purchase only those that use essential oils or herbal extracts.
Avoid brands that contain the word “fragrance” on the label. This ingredient is not a green and healthy option for you or your family.
Synthetic fragrances can negatively affect hormone health among other risks.
Be aware that some brands market Castile soaps that are healthy and others that are not.
Yes, even within the same brand, you must double-check ingredients to be sure the one you buy is truly green!
If you are unsure about the brand you use, be sure to check it in the Skin Deep database for peace of mind! (4)
Most Popular Uses
The savvy consumer can find dozens of uses for Castile soap around the home. The top 10 most popular uses include:
- Bathing (including washing hands – MUCH healthier and greener option than probiotic-stripping anti-bacterial soaps!)
- Shaving
- Brushing teeth and gums
- Washing produce
- Washing dishes
- Laundry
- Mopping floors
- Bathing pets
- DIY pest control in and around the home and garden
Do you use Castile soap? If so, do you make it yourself or purchase from the store? What are your favorite ways to use this green cleaner around your home?
(1) Hot Process Method for Making Castile Soap
(2) Sodium Hydroxide (Lye)
(3) Fragrance
(4) Environmental Working Group Product Database
I found this on Dr. Bronner’s website, a few of these were listed on the bad list, so I am confused on what to use. I also thought I read where the soap should only have 3 ingredients. Even the Dr. Kirk has a lot of ingredients in it.
Water, Organic Coconut Oil*, Potassium Hydroxide**, Organic Palm Kernel Oil*, Organic Olive Oil*, Organic Hemp Oil, Organic Jojoba Oil, Citric Acid, Tocopherol
*CERTIFIED FAIR TRADE INGREDIENTS
**None remains after saponifying oils into soap & glycerin.
I know this is not a question about soap, but I need to find a flea treatment for my dogs, my big boy (Rottie) has breathing troubles when I put Advantix on him and prefer a natural solution that really works……..PLEASE HELP
Here are two posts on controlling fleas naturally both in the home and on your pet. Hope they help! https://www.thehealthyhomeeconomist.com/natural-nontoxic-flea-infestation-solutions-for-home-and-pets/
https://www.thehealthyhomeeconomist.com/safe-flea-control-no-pesticides-drugs/
I have made my own organic soaps for over 15 years and am not enamored with traditional Castille made exclusively with olive oil. Pure olive oil derived soaps have excellent conditioning characteristics, but are not as good for cleansing. All oils include various acids which offer different properties to the soap including cleansing, conditioning, fluffy and stable lather, and bar hardness. The best recipes use a mixture to ensure the soap has all the essential properties. My best soap recipes typically include coconut, olive, palm, and small amount of grapeseed and castor oils. I only use organic essential oils if scent is desired.
Here are a couple links that are useful. The first is a chart of oil properties. The second offers descriptions of each oil and the amount that may be used in a recipe.
millersoap.com/fatacidtab.html
soapqueen.com/bath-and-body-tutorials/tips-and-tricks/free-beginners-guide-to-soapmaking-common-soapmaking-oils/
While Dr. Bronner’s blue bottle of unscented Pure Castile Soap is a recommended purchase, it does contain citric acid as an ingredient. In the article above, citric acid is listed is an ingredient of concern. Is it still okay to use?
I do not recommend ingesting citric acid as it has MSG residue (unless made from fruit), but when nonGMO it is fine as an ingredient in my opinion. There is no issue there unless one is allergic to corn.
Thank you for this informative post. You said that canola oil soap might be gmo, if it is not organic. If I may point out, even if it is organic, canola oil is a gmo oil. It is genetically modified version of the rapeseed plant, modified to be ‘less toxic.’ There is no real canola plant in nature. Canola stands for ‘Canadian oil.’ Thought you might find this interesting. Looking forward to reading more posts.
Canola if organic is a hybrid of rapeseed, not a genetically modified version. Hybrid plants and GMO plants are very very different. Hybridization has been occurring for thousands of years. This is a frequent point of confusion. People call wheat GMO for the same incorrect reason. Wheat is currently not GMO, it is hybridized (all except einkorn wheat), but it is not GMO.
Wow, you are right. I thought I researched it so carefully before, but there is a lot of misinformation out there. Thanks for the correction. I hate sharing inaccurate info.
For those who cannot make Castile soap but want the health benefits of gentle cleansing:
I recommend an “Oil Shower” to my esthetics clients when they complain of dry skin. It’s especially effective in winter. Prime the shower so the water is warm upon entering. Then massage coconut oil all over the body while still waiting to enter the shower. Get your back or at least your shoulder blades if you can’t reach your back. Do your whole body, all the nooks and crannies and avoid the soles of the feet. Slipping in the shower is not fun. Then enter the shower and work the oil into the skin and allow it to melt in and down the body. DO NOT WASH THIS OFF!! This IS the soap. When you feel the oil has been sufficiently spread and the excess rinsed off, exit the shower and pat lightly with a towel. Do not rub the residue off. Then go on with your primping. The shower has nourished and cleansed the skin, rehydrated and sealed your body and the kicker is those feet! Better then the best peri will reveal. Guaranteed.
Im wondering what this oil does to the plumbing/ septic. Anyone know?
This will KILL your plumbing and septic. Never dump or rinse coconut oil down your drains!
Why should coconut oil ruin plumbing? If will remain liquid at Temps in the 70’s so should easily flush down the drain without solidifying. Not sure what the concerns you have.
All soaps are a mix of fat or olive oil and caustic soda. It’s a similar principle to mixing petrol with dishwash soap to make a good hand degreaser for home mechanics. Always rinse your dishes to get rid of the soap residue.
I would advocate not using any soaps at all if you can avoid it. The less you take in the shower, the better! Hot water and a body brush are quite sufficient.
Sorry, but this makes no sense and is not backed up by science. First, there are no oils present in real soap unless the recipe has been superfatted as the saponification process converts the oils to soap. Second, there are various substances that cannot be removed from the skin with only water/without the use of soap or a surfactant (I don’t advise using surfactants or common store soaps). Finally, if you use a high quality, genuine soap, your skin is not only cleansed, but receives the conditioning benefit of the glycerin.
Thank you for this article. I so appreciate it. I’ve always been confused about using Dr. Bonner’s soaps. Are they suppose to be diluted in water or are they ready to use? The bottle says, “Three times more concentrated than traditional soaps Dilute with water.” On a different side of the bottle where it discusses the uses it says, “Face and body wash: Get wet, apply soap to hands, washcloth or loofah.” For washing vegetables it says, “Add three dashes to a sink full of water.” For household cleaner it says, “Dilute soap with water 1:40 for light cleaning, or use full-strength for heavy-duty, grease-cutting jobs.” It sounds like I can use the soap on my face without diluting it but I should dilute it if I’m going to wash my vegetables with it or clean my house with it. Am I understanding this correctly? Can you refer me to a website that explains how to use Dr. Bronner’s soaps?
The Kirk’s Castile soap bar I have says the ingredients are: coconut soap, water, Vegetable Glycerin, Coconut Oil, natural fragrance” I thought “glycerin” and “natural fragrance” were two ingredients we should be concerned about. Thank you for allowing me to rattle off so many questions. I appreciate your input.
The Kirk’s Castile soap I looked at had no fragrance. Definitely do not buy if it lists fragrance. Buy the unscented one or a bar that has the specific essential oils used for fragrance listed on the label.
Also, here is a link to Dr. Bronner’s dilution cheat sheet: http://www.lisabronner.com/dilutions-cheat-sheet-for-dr-bronners-castile-soap/
Caustic soda may be produced on a large scale in chlor-alkali plants using mercury cells, and thus there is a risk of mercury contamination: ncbi.nlm.nih.gov/pmc/articles/PMC2637263/pdf/1476-069X-8-2.pdf. Incidentally, the raw materials produced in chlor-alkali plants are also used in the production of high fructose corn syrup, which is a very alarming story in and of itself since many samples HFCS were shown in this article to contain significant amounts of mercury. The fact remains, anything produced using mercury cell technology may be contaminated with mercury.
I’m glad to know that Kirk’s Castile soap is one you recommend. As I was reading the article, I started wondering about my Kirk’s and was just about to jump up to investigate it when it showed up under Dr. Bonner’s in your post. Kirk’s and Dr. Bonner’s are the only two soaps I’ve bought for the last few years for our household. Sorry, I take that back. I buy Zote for making my laundry detergent. But I have thought about using Kirk’s in place of the Zote. Kirk’s is quite reasonably priced, works well, smells good and lasts a reasonable amount of time. I unwrap the bars when I get home to give them a chance to air dry and harden up a bit which seems to extend their lifespan. We tend to use Dr. Bonner’s liquid more for cleaning the house than for cleaning people, lol!
Thanks fro the input Kim!