Back to Basics: What Is Soap and How Does It Work?

Soap - it’s something that we all use everyday. We accept that it makes us cleaner than just plain water - but how? What IS soap anyway?

soap

The FDA defines soap as “the alkalai salts of fatty acids”, which may or may not clear things up for you depending on how long ago your last chemistry class was.

“Soap” is what you get when you combine a fat or oil (fatty acids) and lye (an extremely strong “alkalai” or “base”). That’s all you need to make soap - fatty acid, lye, and a liquid (often water - though in The MacBath’s case, goat’s milk, which has more fatty acids of its own!)

“Uh huh”. I hear you say. “I don’t see any salt whatsoever on that ingredient list. How can soap be a salt? I sprinkled it on my baked potato and it was awful!” First of all, stop tasting your soap. (I promise that no matter how good it smells it tastes terrible.) Second, ordinary table salt (sodium chloride or NaCL) is just one example of a “salt”. You might recall that, in chemistry, any combination of an acid and a base makes a salt. Soap is a combination of a weak acid (fatty acids) and a strong base (lye), which results in what is known as “alkalai salt,” or a salt that is basic on the pH scale. (See scale below) Sure enough, if you use a pH strip (also known as a litmus test) in soapy water, it often scores an 8 or 9.

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“Whoa whoa whoa” I hear you cry. “I’ve been putting a base on my delicate skin all of these years? That sounds dangerous!” I promise you, you’re fine. “Acid” and “base” might sound like scary words, but you regularly consume weak acids and bases in your food every day. Soap is actually around the same pH as baking soda!


Ok, so I guess I’ve been washing all my life with "alkalai salts". How the heck does that get me clean?

soapyhand

Soap has two main mechanisms of action, both of which come from it being a surfactant, which comes from the words "surface active agent." The defining property of surfactants is the unusual ability to bind to both oil and water, which is the first and most important mechanism of action. Have you ever heard the phrase “they get along about as well as oil and water”? You know how you always have to shake up salad dressing before you pour it because it always separates into two layers? It’s because oil molecules and water molecules don’t like to mix! If you wash with plain water, it’s not getting all the oily goop off your body. That’s where soap comes in.

One end of the soap molecule is hydrophilic (water-loving) and binds to water (the black dots of the drawing below). The other end is hydrophobic (water-hating) hydrocarbon chain that binds to oil molecules (the purple tails in the drawing). This forms a cluster called a “micelle” — a ring of soap molecules surround the drop of oil, creating a bridge between oil and water. Thus, when you rinse off soapy water, it takes the oil with it. And ta-da! You’re clean.

A soap micelle. 

A soap micelle. 

The other mechanism of action is that it reduces the surface tension of water. Water molecules like to stick together — it’s why water beads up on your cold glass instead of spreading across it uniformly. Some people like to say that soap “makes water wetter” — what they actually mean is that by introducing soap molecules to water, the micelles force the water molecules spread out.  If you’ve ever seen a water bug walking along the surface of a pond, this is because the water's surface tension can support the weight of the tiny bug. If you mixed soap into the pondwater (but, um, don’t), the water bug would slip right through the surface. The decrease in surface tension allows soapy water to get into more nooks and crannies than water alone.

If soap is just fats, lye, and liquid, then what is this “sodium lauryl sulfate” stuff I see on my soap packaging?

sodium lauryl sulfate

Ah, well, if you have sodium lauryl sulfate (abbreviated as SLS) in the ingredients list of your soap, bodywash, or shampoo, then The MacBath regrets to inform you that you do not actually have any soap—at least according to the FDA. What you’ve got is a synthetic detergent, which is also a surfactant — it has a hydrophobic and hydrophilic end — but it can react differently.  If you’re not sure if what you have is a soap or a detergent, give it a test with a pH strip - detergents are neutral or acidic, whereas soap is always basic.

There are actually very few true soaps on the commercial market in the USA — nearly all the products available are synthetic detergents (yes, even your bar soap!). There are a two main reasons for this. One is that detergents are much cheaper to manufacture. Second, detergents perform differently than soap in extremely hard water — water heavy in minerals. If you have hard water that contains magnesium and/or calcium ions, the hydrophilic end of the soap molecule (Na+COO-) reacts with these ions to form soap scum. A detergent, whose molecule has a different salt at the hydrophilic end (Na+SO3-), won’t react with them the same way and won't produce soap scum. This must seem like a no brainer to commercial manufacturers — cheaper to produce AND works the same in any kind of water? Sign me up!

But — and you must have know there was a “but” coming — there are also downsides. Detergents are much more drying on the skin, and strip more of the body's natural oils. They’re also not as eco-friendly as soap — detergents take longer to break down and are harder on the environment when they get into the water table. Liquid detergents, such as shower gel and body wash, also require significantly more packaging than solid bar soaps, creating more waste in landfills So if your skin is dry or sensitive, or you’re trying to reduce your carbon footprint, you may want to give soap a try. Your skin and your planet will thank you.

Fantastic Review on Scarlet's Letter!

Amber of the blog Scarlet's Letter just wrote a fantastic review of three of The MacBath's Harry Potter soaps. She writes:

"I used to buy soap from that one super popular soap store that a lot of people love, you know the one I’m talking about, but honestly, I love this brand so much better. The scents are great, the quality is awesome, and I love the more natural ingredients. The MacBath is one of my favorite handmade soap brands I’ve tried."

Read the full review here!

 

Marketing to Men - a Conundrum of Conflicting Values

With Father's Day on the horizon, I was planning to feature The MacBath's shave soaps on social media - many Dads are men! Many men shave! It seemed like a no-brainer.

But then I hit a snag. What, exactly, should I say about this soap in an attempt to appeal to a population buying almost exclusively for men? I have been following the #masculinitysofragile movement with great glee (buzzfeed does an excellent roundup here and here - go and enjoy a good laugh at what marketing departments think the average cis male needs to make a purchase.). I didn't want to fall into any of these lazy gendered marketing pitfalls by trying to position the soap as "ultra manly" or using violence and danger as shorthand for "men". (See the grenade shaped bath bomb in the buzzfeed article above.)   

So on the one hand, I'd like to get some shave soap in the hands of some Dads on Father's Day. On the other hand, I don't want to stoop to weird gendered marketing tactics that reduce all men everywhere to a caveman stereotype. So what's the solution?

I hope that you like what I came up with. I present to you: The MacBath's first ever commercial.

 

 

What Can You Do With Leftover Soap?

Soap scraps have been piling up here at MacBath headquarters . I've got stacks of loaf ends, leftover soap batter that didn't quite fit in the mold, and bars that didn't stamp cleanly or acquired a small scratch - all perfectly good soap that smells great and will get you clean, but not up to the high aesthetic standards that I set for sale.  

So what's a soapmaster general to do? Aside from using them in my own shower, tossing small scraps in with my laundry, or placing multiple bits in a bag for travel or camping, there is another option to take leftover soap and make it into something completely new - hand milling.

Step 1: Grate, grate, grate. Are you tired? Too bad, keep grating.

Step 1: Grate, grate, grate. Are you tired? Too bad, keep grating.

So what the heck is hand-milling?

To make hand-milled soap, your base soap is reduced to small grated shavings that are melted down into a thick paste. Once the soap is melted, the soapmaker can add any scents, colors, oils, or other additives that they desire and re-mold the soap batter. There are some excellent benefits to putting your soap through the hand-milling process: it reduces the amount of moisture, resulting in a harder and longer lasting bar, and the second heating often results in a milder soap. Additionally, people who don't want to work with lye can still have the experience of soapmaking. And while cold process soap has a 6 week cure time, hand-milled soap can be used immediately (as long as the base soap was fully cured prior to grating.)

I took an early experimental batch of my Holmes soap (it had come out a little too hard to stamp cleanly) and began to grate. 

Yes sir, yes sir, three bags full.

Yes sir, yes sir, three bags full.

Many hours of grating later (and many grated knuckles), I had three gallon-sized ziploc bags full of deliciously scented goat's milk soap. After admiring my handiwork, I double bagged the soap for safety and inserted the bags into my crockpot and canner. I filled them with water and started boiling!

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I boiled the soap bags for about an hour and a half until they were nice and mushy. Wearing heat proof gloves, I removed the bags and kneaded them until the soap inside was a smooth paste. (Alas, I have no photos of this step as my hands were full of hot soap).

Once thoroughly mushed, I opened each bag and added 4 teaspoons of almond meal to act as a natural exfoliant. After thoroughly kneading the soap a second time to evenly distribute the almond meal throughout the batter, I cut the corner off of the bags and piped the hot soap into my cylindrical molds. 

Several hours later, I unmolded the soap to reveal super scrubby goat's milk and almond meal soap scented with vanilla and rosewood. It's going to be perfect for getting the dirt off of my hands after a long day in the garden.

Finished Soap

It's quite a transformation from a disappointing, unstampable batch of Sherlock Holmes soap to a completely new, scrubby and exfoliating soap! It's harder, which means that it'll last longer, and milder as well. Plus I really enjoy the more rustic look. If you've wanted to get into soapmaking but have been wary of the lye, I highly recommend giving hand milling a try. 

The MacBath is Open For Business!

There's nothing that I love more than handmade soap. Except for maybe books. And computer design. And finally, I can combine all three into one product! 

Each batch of my goat's milk soap starts with a favorite literary quote, image, or idea — I brainstormed my first soap, "Scourgify!", as I stared in despair at my sink full of dirty dishes and wished for a wand.

First view of the Scourgify stamp in TinkerCAD - still to be printed and tested..

First view of the Scourgify stamp in TinkerCAD - still to be printed and tested..

I next design a soap stamp in a CAD drawing program and manufacture it using a 3D printer — each stamp design is 100% unique to the MacBath!

The first stamp test on a batch of plain goat's milk soap - stamp is lookin' good!

The first stamp test on a batch of plain goat's milk soap - stamp is lookin' good!

Finally, I combine color and scent in a soap design that brings the source text to life. How do I want this soap to make people feel? What smells might they associate with their favorite book or character?  In the case of "Scourgify!", I wanted a a cheerful yellow look with a nice homey scent - warm and cozy, just like Molly Weasley's kitchen at the Burrow. 

The final soap design - yellow from exfoliating dried lemon peel, stamped with merlot colored mica, and scented with citrus-y japanese yuzu.

The final soap design - yellow from exfoliating dried lemon peel, stamped with merlot colored mica, and scented with citrus-y japanese yuzu.

And voila! Creamy, lather-rich goat's milk soap that gets you clean and smelling great while showcasing your love of literature. Check out the shop for more soapy homages to my favorite books, plays, and poems.

"Beneficial to All Ingenious Persons of the Female Sex"

As a soapmaker and librarian, when the time came to develop a logo for the MacBath I naturally turned to historic books for inspiration. The Folger Shakespeare Library has an amazing collection of digitized texts that were ripe for the plundering. (What? You've never browsed their digital collection? Stop reading immediately and GO FORTH. I'll wait.)

I was delighted to discover multiple bookplates, texts, and recipes written by women for women during the Elizabethan and Restoration eras, just waiting to be rediscovered. One of my favorites was the frontpiece for "The Queene-Like Closet or Rich Cabinet" written by Hannah Woolley in 1675. Just look at those gorgeous illustrations!

Queene-Like Closet

 

Full title: "The queen-like closet, or Rich cabinet: stored with all manner of rare receipts for preserving, candying and cookery. Very pleasant and beneficial to all ingenious persons of the female sex." - Hannah Woolley, 1675

I took an excerpt from this page as The MacBath's logo, to honor the generations of women making soap and passing on their knowledge to the rest of us. We may have access to ingredients that they never would have dreamed of, but the basic process remains the same. When we study the 17th century, the lives and accomplishments of craftspeople are not usually in the curriculum - but that doesn't mean that we don't have records of their lives and accomplishments! As an "ingenious person of the female sex", I'm thrilled to read Hannah Woolley's words almost 350 years later and to make her work the face of my company.