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The Scoop on Suds. How Does Soap Work? (Fight Club Edition)

How Does Soap Work?

For such a common household item used to clean just about everything, it appears that few people actually under how soap gets things clean. Therefore, we have decided to look at the question of how does soap actually work? Surprisingly, the mechanism of how soap removes dirt and grime is actually pretty simple. The key to the effectiveness of soap is in its structure. The explanation will require a bit of science knowledge, but nothing too advanced, and we’ll do our best to explain it at an easy level!

It’s all about the fat

Not only is fat delicious, it is the most basic cleaning component of soap. Kind of surprising right? Think about what happens when oil is added to water. The oil tends to collect together into circular droplets right? That right there is the key to how soap gets things clean. So how does this work? Let’s dive into the soapy details.

Fat is bipolar

So here is where it gets a bit technical, but bear with us, it’s actually pretty straight forward.

When you hear bipolar, you usually think of a condition that has two extremes. This is actually pretty accurate regarding soap. As mentioned above, fats are the cleaning ingredient in soap, and fats contain two main sections. A water-repelling, hydrophobic (think phobia like fear) tail, or multiple tails; and a water-attracting, hydrophilic (think audiophile) head group. This structure looks like like a pin. We call this mix of water-attracting and water-repelling bipolar, and it is this bipolar makeup of fats that is key to their usefulness in cleaning.

single-tail-lipid
This is what your butter is made of.

The proof is in the pudding (that’s being washed away with soap)

So we’ve established that fat is the cleaning ingredient in soap, and we’ve looked at the structure of fat. So how does this tie into the actual cleaning process? We turn to bubbles for the answer (no, not the Trailer Park Boys character).

When you lather up soap, you see bubbles forming. The bubbles are what actually carries away the dirt, grime, dust, bacteria, viruses, and whatever else is on the surface. So why do the bubbles form, and why do they trap refuse? The answer is fat, and its structure.

We discussed above that fat has a water-repelling tail. So if it repels water, what is it attracted to…? The answer is things that aren’t water (obviously, right?). So what is not water…? Things like dirt, dust, grease, viruses, bacteria, various stains, just about everything, are not water. This relationship between on end being attracted to water, and the other end being attracted to everything else, is what results in the formation of bubbles.

All of our effort goes down the drain

So how do the bubbles actually form? We have looked at how fats interact with their cleaning surface, but how does the shape of bubbles form? The answer, once again, is in the structure of the fats (surprise). We discussed above that the water-repelling tails are attracted to non-water (everything else), but we have to consider the relationship in 3D. When water is present, fats turn their water-repelling tail away from it, but how does the tail get away from water that approaches from all side? They protect themselves by working with other fat molecules. The molecules line up, presenting their water-attracting heads outwards, and shielding the water-repelling tails inwards. What does this line of fat molecules look like? A bubble (surprise again). More correctly, this structure is called a micelle.

This sounds way more complicated when written, so here’s a great diagram that shows how this works:

soap-micelle
Pretty straight forward, right?

The image above makes it look like the bubble has holes, so here’s a more accurate 3D model:

soap-micelle
From Buzzle.

Basically, the individual molecules are squished together so tightly that the tails are protected inside the bubble structure. As mentioned above, non-water dirt, grime, etc. is attached to the tails, so when these structures form, it traps them inside the bubbles. Then, when you go to rinse the soap away, all of the filth is rinsed away as well. Buzzle has a pretty great look into the more specific details that determine micelle formation, in case you’ve suddenly become super interested in soap.

What about antibacterial soap?

antibacterial soap is guaranteed to kill germs and keep you healthy, right? Well, yes… but no. Antibacterial soap is definitely useful in certain instances, but it’s use can actually cause problems, and make you more prone to getting sick. Montepellier Maids have a great write up on antibacterial products, and why their benefits are not always clear.

Why do you know so much about soap?

Well, because it’s our job! We make sure we know how the products we use work, that way we can select the best (and avoid the worst) when cleaning your home. So leave the soapy business to us, and head to www.westmaids.com to book your clean in less than 60 seconds.

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