The Life of a Bar of Soap

(Posted 3/6/07)

I wanted to carefully track the life of a bar of soap.

I've long had a theory that bars of soap start deteriorating faster after you can no longer read the words imprinted on them. I think I got this idea from something Andy Rooney said years ago, but I can't find it now. Regardless, the theory made sense to me, because I figured that the ratio of surface area to volume went up as the bar deteriorated.

Fianlly I decided to test it.

 

 

I got myself a bar of soap. A brand new bar! This was going to be exciting!

 

 

 

 

The piece of equipment that was really going to make this experiment fly was the "Dry Bar".

This piece of molded acrylic would help keep me from losing soap mass to the soap dish in the shower.

The packaging claims that it "Makes Soap Last 22% Longer"

That sure sounds likea made-up figure to me. I'll test that claim some other day.

 

 

 

 

Now I was ready to start my measurements.

The box said that the bar of soap weighed 4.5 oz.

 

 

 

 

 

In case you're wondering, the bar of soap, with the box, weighed 4.60 oz., so that doesn't explain the discrepency.

 

 

 

 

 

Then I got myself a kitchen scale. Looking back on it, I have two regrets about this scale:

1. It was only accurate to .05 oz. - Plenty accurate for a kitchen, but I needed more.

2. It measured in ounces. What the hell? Who does anything that is even vaguely scientific using English measurements? Sorry 'bout that.

 

 

 

Finally, I made myself a data sheet.

I needed to track the data in the bathroom, where my computer doesn't like to go. So I was going old school, with paper and a pen.

 

 

 

 

 

 

But my scale disagreed.

 

My first measurement said the soap weighed 4.20 oz.

Either my scale was inaccurate or a major American manufacturer was misleading the public with their advertising.

I chose to believe that my scale was wrong. But I stuck by it for the rest of this experiment.

 

 

 

Next I installed the "Dry Bar" by peeling the adhesive strip and pressing it into place out of the stream of the shower.

For some reason, this installation took me hours. I'm not very handy.

 

 

 

 

 

Now I was ready to start taking showers and collecting data! I decided not to take a whole bunch of showers all at once. Instead, I decided to spread them out on a roughly daily basis. This worked well for me.

Three things you should know about my showering habits:

1. I subscribe to the "top down" theory or showering. I shampoo my hair and then start washing my face and work down to my feet.

2. I don't use a washcloth. I rub the soap directly on my body. Long ago I decided that this was the "manly" way to shower because that's how the guy on the Irish Spring ads did it. You can see how this might affect soap usage, though. Someday I'll test that.

3. I'm fairly hairly. Not Robin Williams hairy. But at least Jerry Seinfeld hairy.

 

 

 

 

 

I started taking showers and recording both the starting weight of the soap and the end weight of the soap. This way, I could account for any mass loss due to drying in between showers.

After 3 showers ->

 

 

 

 

 

At the beginning of my 14th shower, the bar was down to 2.10 oz. Half of the starting weight. I was already getting sad to see it go. But it didn't look a lot different to me than it did at the beginning.

 

 

 

 

 

But as it got down, it started getting sharp.

Sharp enough to cut butter.

 

 

As the soap got smaller, I started seeing its last days coming.

And I was sad.

I really thought this was the last shower it would have.

 

 

 

 

 

But somehow, the bar lasted through this shower.

By the end, it weighed only .05 oz.

With my scale's margin of error, that was equivalent to zero.

 

 

 

 

 

<- After 4 showers, the words on the bar were already almost gone. If I were to subscribe to Andy Rooney's theory, I should discard it now.

Man, you could spend a lot of money on soap that way.

 

 

 

 

By the time I got to my 20th shower, the soap was down to 1/4 of its original weight.

It was still pretty usable, though.

No sharp edges yet.

 

 

 

But not sharp enough to cut an apple.

 

 

Normally at this point I would employ what I call the "piggy-back technique", whereby you place the sliver on top of a full bar of soap and hold it there during a shower, so that it becomes bonded with the larger bar. This eliminates any soap wasted.

 

 

And so, before my soap's actual last shower, I realized that I had grown close to him.

I had started to see him as a living being.

I saw his unique personality.

And I knew that he'd like to say good bye to all of you himself.

So I gave him an arm and a face and told him to bid you all adieu.

 

 

And with that, I took my last shower with Tony.

What did the chart say?