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What does shaving cream do?

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📓 The short answer

Shaving cream is a specially designed soap that forms a dense, long-lasting foam. It lifts hairs for a smoother, closer shave, hydrates and protects your skin, and cleans away oils and debris as you go.

📚 The long answer

Humans have been shaving for thousands of years, but the shaving cream we use today is a modern luxury. Ancient Egyptians used a mix of animal fat and wood ash to get a close shave, and the Greeks and Romans shaved with olive oil and sand.

Your nice, white, fluffy cream sounds pretty great by comparison. But, how does shaving cream help you get a close, painless shave? Let's start with the basics.

(By the way, if you don't care about the chemistry, feel free to skip down past the section with these emojis 👃🎨❌🦠).

What is shaving cream?

Shaving cream helps lubricate the skin to allow for an effective shave. Here are the main ingredients and the role they serve in the shaving process.

🧼 Soap: After water, soap is the main ingredient in shaving cream. Soap is a surfactant, which reduces the surface tension of water so it can mix with water and wash away oil and dirt.

At a molecular level, soap has a hydrophilic head (bonds with water) and a hydrophobic tail (repels water and bonds with oils and fats).

When you use soap, you'll notice how it quickly forms bubbles. That is because the hydrophilic heads are attaching to water in a way that traps an air bubble.

Unlike bar soaps which create easy-to-pop bubbles, shaving cream soap is specially formulated to create lots of long-lasting bubbles. A popular soap used in shaving cream is triethanolamine stearate, a combination of bubble-producing triethanolamine and bubble-stabilizing stearic acid.

Unlike smaller ions that dissolve readily in water, triethanolamine's bulky molecular structure spreads its charge over a larger area, creating weaker interactions with water molecules that make it less water-soluble. This is why triethanolamine helps create more bubbles. And you'll notice that the stearic acid portion has a very long chain. This makes the hydrophobic end of the soap molecule even more resistant to water, keeping the bubble's structure.

In short, this special soap reacts with water to produce a thick layer of tiny bubbles, creating a dense foam that lasts for the duration of your shave.

🧴 Lubricants: Many shaving creams also add extra lubricants for a smoother shave. A common lubricant is glycerol, which is a thick, syrupy liquid with hygroscopic properties (i.e. it attracts water).

Other shaving creams use aloe vera or coconut oil to achieve the same silky, hydrating feel.

🫧 More foaming agents: While I'm sure Spongebob's fail-proof bubble-blowing technique was considered, shaving cream producers instead opt to add more chemicals to boost the bubbles during your shave, including laureth-23, a common foaming agent.

Laureth-23 works to add more bubbles thanks to its extra long tail of hydrophobic fatty acids.

👃🎨❌🦠 Fragrances, coloring, antibacterials: Shaving creams also include other ingredients like fragrances to smell good, colors to look pretty, and antibacterial substances to reduce the likelihood of infections after a nick.

What does shaving cream do?

So we've learned that shaving cream is essentially lubricated soap that's supercharged to create lots and lots of strong, tiny bubbles. But why all the bubbles and what do the other ingredients do? Here are the main purposes of shaving cream:

#1 Lubrication: Shaving cream creates a layer of protection between your skin and the blade. The lubricants included in shaving cream, like glycerol, coconut oil, or aloe vera, allow for a more comfortable, close shave and leave your skin feeling smooth.

#2 Hydration: Dry hair has about the same tensile strength as copper wire, but it can be softened by getting it wet. The surfactant properties of soap not only create bubbles but also act as wetting agents, allowing water to spread more easily.

This ensures your skin and hair can get (and stay) plenty wet during the shave. This hydration increase the chances of a close shave by saturating the hair follicles, as well as reduce the chances of hairs pulling.

#3 Lifts hair away from skin: The bubbles in shaving cream also play an important role. The thick layer of tiny bubbles physically lifts the hair away from the skin, which allows them to be shaved more effectively by the blade.

#4 Shows you where you've already shaved: The white foam provides a clear guide on where you've shaved and where you haven't yet. This reduces the chances of you missing a spot or unnecessarily re-shaving the same spot, which could lead to skin irritation.

#5 Cleans your skin: After all, shaving cream is mostly soap. A nice shave adds the bonus of washing away any oils or grease, leaving your skin cleaner.

--- Thanks for reading this week's newsletter! If you have any thoughts, questions, or favorite GIFs, my inbox is always open. Just hit reply to send me a note! :) ​ All my best, Caitlin ​Click here to read five facts about Caitlin​

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​Sources for this week's newsletter​

🌐 Wikipedia article of the week

​Hypoalgesic effect of swearing​

"Research into the hypoalgesic effect of swearing has shown that the use of profanity can help reduce the sensation of pain. This phenomenon is particularly strong in people who do not use such words on a regular basis....Swearing in response to pain may activate the amygdala which in turn triggers a fight-or-flight response. This then leads to a surge in adrenaline, a natural form of pain relief."

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👀 Catch up on other curious questions

• ​Why do clean sheets feel so good?​​
• ​How do thermal printers work?​​
• ​Why do joints crack?​​

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