Soap by any other name would smell as sweet...or would it?
Today, I officially launch the Horsethief Canyon Soap Company blog. The idea itself is a bit daunting, but to anyone who knows me, I kinda like talking about soap. Like a lot. What can I say? I’m a sharer. Hope you don’t mind.
In light of this monumental occasion, it seemed only appropriate to kick this thing off with a little soap science lesson. Whoa. Wait. Stop. Don't hit the "Back" key yet. I know it sounds like a snooze-fest. But if my kiddo can make it through this soap lesson, I'd bet you can too. Yeah. That's right. Gauntlet=thrown. Can't back down now. If the kid can do it...so can you. And maybe you'll even like it.
So, here's the thing about soap...it's been around forever. Like"FOR-EV-ER"
(The Sandlot, anyone?). Roman legend references "Mount Sapo" where the fat from the ritual animal sacrifices mixed with the ashes from the fires and filtered down the stream making laundry day a lot easier for the women of the villiage. No one is really 100% sure that the legend is true, but it seems logical enough. There is, however, actual evidence of conscious and proficient soapmaking from the time of the Babylonians around 2800 BC. Like I said..."FOR-EV-ER".
To Saponify, or not to Saponify...that is the question.
Saponification (sounds a lot like Mount Sapo, doesn't it?) is the reaction between an acid and a base to form a salt.
The acid=fat/oil.
The base=lye (sodium or potassium hydroxide).
The salt=soap
Basically saponification is the formula for soap. Simple formula, right? So soaps really can't be all that different, can they?
Ummm...are chocolate chip cookies delicious? Yes. Yes they are.
First, soaps can be formulated about a million and one different ways. Starting with the “acid” (or fat/oil) component, you can make soap from any variation of animal or plant based oils/fats known to man (not from petroleum based oils though). As we can see from Mount Sapo, the original fat was animal-based because it’s what was readily available. Animal fats (or tallows) are still used in some commercially available soaps and despite the “ick” feeling some have out this, tallow is an excellent soapmaking fat given its high stearic acid content (a fatty acid responsible for providing ultra-emolient and conditioning qualities) as well as its ability to produce a very hard, long-lasting bar.
Plant-based oils have a huge and varied list of pros and cons and this is why most artisanal soapers choose a variety of oils in their recipe formulations. The idea is that they capture the best features of some oils while using other oils to compensate for some of the less-desirable qualities.
Examples:
Olive Oil is a super-gentle cleanser, great for babies and sensitive skin. But, it makes ZERO lather/bubbles. It has a more slimy feel to it when wet. As someone with uber-sensitive skin, I LOVE the idea of olive oil soap (i.e. “Castile” soap), but I suspect only the most educated of soap-enthusiasts would be ok with the whole no-bubbles thing. It also can make a very soft bar of soap unless aged/cured for a VERY, VERY long time.
Coconut oil, on the other end, can lather in ocean water (or so they say…I’ve never actually tried since most beaches I frequent have lots of people and taking a bath there would just be awkward). This makes it an exceptional choice for harder waters. It produces a very, very hard, white bar of soap (excellent for longevity). It’s considered the workhorse of “cleaners” dissolving almost anything it comes into contact with (motor oil, grass stains, etc.) making it an excellent choice for laundry soap. The downside to a soap make exclusively with coconut oil is that it can dissolve every stitch of natural oil on your skin leaving you dry and irritated (unless formulated carefully to address this issue-this involves superfatting and we'll address this in a later blog-post).
These are just two of the more “extreme” examples. Interestingly, the “pros” of these two oils make them two of the most commonly used soaping oils and as mentioned above, are used to “counteract” eachothers less desirable qualities. Other oils/butters are known for their conditioning qualities. Some for providing bar hardness without drying the skin. Some for creating a creamy lather and some for creating big, lacy bubbles. Like craft beers, the variations are endless (and mostly fabulous, albeit not quite as delicious).
Now what about this “lye” component? I mean, isn’t that dangerous? Well, by itself, YES! This is why The Hubs calls me Laverne and/or Shirley when I’m making soap…scrub cap, goggles, lab coat (or apron), respirator and elbow-length gloves. Handling raw lye (or lye-water) is no joke and should always be approached with caution. But something magical happens when you introduce this lye-water to your soap oils: it begins to transform! The formal name for the reaction is “Saponification” (sound familiar?) and as this happens you no longer have lye molecules AND oil molecules. They come together to form soap. Some folks are terrified of the idea of using “lye soap”. “I mean, won’t it be drying and irritating?”. No! As long as the soap is properly formulated, there is no lye left in the soap after saponification occurs! It’s just SOAP now!!
So what is lye, anyways? Traditionally, lye was the result of boiling hardwood ashes. There are two types of lye used in soapmaking: Sodium Hydroxide (for hard bars of soap) and Potassium Hydroxide (for liquid soaps and shaving creams). It’s no longer made by boiling ashes, but manufactured in lab settings to ensure consistent quality and purity. This matters since calculating the exact amount of lye necessary to "saponify" a certain amount of oils is critical to formulating a safe and good quality bar of soap. More on this to come...
Whew. Ok. So to recap, we now know that soap is an acid (oil/fat) combined with a base (lye or “sodium hydroxide”) to form a salt (soap). Glad we made it through that…I was starting to feel like we were in high-school chemistry again…only I was the teacher. And that folks, is just terrifying. But, in the interest of greater education, I’ll try and hold this “chemistry class” together a bit longer so we can learn a few more things about soap…and non-soaps.
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Soap label made for a soap science day at our local charter school.
A recap of the "Saponification" formula was added to help students remember. |
So what makes soap, soap?
In order for it to be considered soap, we know it has to meet the above definition (acid+base=salt). Notice I didn't say Sodium Lauroyl Isethionate + Cocamidopropyl Betadine = Beauty Bar (i.e non-soap).
How could something so simple as to happen by accident on an ancient mountain somewhere evolve into something with such big, unpronounceable words? Simple. Those horribly long words that I typed above (that I refuse to type again because the pheonetic composition of such words is positively elusive to me) are not soap. Surfactants, yes. Petroleum-based (usually), yes. Detergents, yes.
Soap? Most certainly not.
So what’s the real difference? To understand this, let’s first learn why soap works the way it does.
Recently, while working with “The Big One” on his science unit, we came across a lesson that so brilliantly and simply explained why soap works the way it does. And despite being a soapmaker, this was new information to me! I mean, I’ve used soap my whole life, but had really never considered why or how it worked.
So here goes:
One of the basic principles of chemistry is “like dissolves like”. It’s the simple explanation for why water on its own cannot free your hand of grease and oils or why some salad dressings will never, ever fully mix no matter how hard you shake them. Oil and water are NOT alike.
So how does soap play a role? Remember the equation above? Acid+Base=Salt. What happens when we introduce salt into water? It DISSOLVES! It’s what we call hydrophilic. Molecules are considered hydrophilic when they contain atom groups similar to water. This is called the “OH” group (or Oxygen Hydrogen group). Since water is H2O, we know it has an “OH” group. Turns out, soap molecules have a few of these “OH” groups as well. Et voila! Part of the soap molecule dissolves in water. Check out the pics from the science unit:
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Images from Dr. Rebecca W. Keller's "Focus on Elementary Chemistry" lesson.
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Whew.
So now we know how soap dissolves in water, but how does that help us dissolve oil? Well, one end of a soap molecule is hydrophilic (water loving), but the other end is hydrophobic (water repelling) and lipophilic (oil loving). And what do we know about chemistry? Like dissolves like.
So what we have is a molecule that dissolves partially in water and partially in oil. And when those molecules team-up, they encircle the oils/greases in a little droplet that can be easily rinsed away with water. Check out the awesome diagrams below.
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| Images from Dr. Rebecca W. Keller's "Focus on Elementary Chemistry" lesson |
Things that are not soap
Now what about those long, unpronounceable words above? Well, here’s a very simplified explanation of what they do. They are surfactants (or detergents) and they basically DO the same thing as soap. They were created during WWI & WWII when there was a shortage of the animal and vegetable fats necessary to make soap. Their advantage is that they are generally impervious to hard water, allowing them to work is almost any water condition (where some soap formulations may not rinse fully in extremely hard water, causing scale). The disadvantage is that they are typically petroleum/hydrocarbon based and full of some other wonderful unpronounceable “goodies” that seem a bit unnecessary to the simple act of getting oneself clean. Before I go any further on this soap box, you should know that there are naturally-derived surfactants (from things like coconut oils, etc.) and there is some excellent information out there about their safety and usage.
*Thank you
www.cleaninginstitute.org for the excellent and simple explanation of surfactants/detergents!
How to tell the difference
So, how do you know what is “soap” and what is “surfactant” by looking at a label? Here are a couple quick tips:
1. If the label is noticeably bereft of the word “Soap”, it’s probably a surfactant-based bar (also called a Syndet, or Synthetic Detergent, bar). From a legal perspective, the FDA does not allow for the use of the word “soap” unless it meets the basic definition/equation from above (acid+base=salt).
2. If you see the word “sulfate” on the label, it’s probably not soap.
3. Words like “Saponified oils of….” would indicate traditional soapmaking as would words like “Sodium Tallowate” which is just a fancy way of saying “Saponified Tallow”.
Class dismissed!
And with that folks, we now find ourselves at the end of this lesson. I don’t know about you, but I am eternally grateful to be a soapmaker, not a chemistry teacher. Like high school chemistry, there are A+ valedictorians reading this and wondering how this is new information for anyone (and if you're in this group, please forgive my VERY basic explanations). But before my soapmaking escapades, I would have been in the other half of this class: knowing deep down in my little hippie heart that not all bars of soap at my local drugstore were not created equal…but not really knowing why. So, now you know. And, according to the GI Joe cartoon, "knowing is half the battle".
*For aspiring soapers, this is most certainly NOT a soapmaking tutorial. Just a collection of soap information. Some of the best resources I have used in my soaping adventures have been from Brambleberry/ The Soap Queen, Anne Watson and SoapCalc.net. I'd recommend starting there!
*The Chemistry unit I referenced above is Rebecaa W. Keller’s “Focus on Elementary Chemistry” program. It’s A-wait for it-MAZING. The content is so aptly broken down that both kids and adults can really access a great deal of information without being overwhelmed or confused. You can find the program on Amazon.
