If you haven’t read “Altoids Tin Waterproofing Experiment,” please do so in order to understand the background for this article.
A reader has suggested that the initial waterproofing test I did with the Altoids Tin was flawed because I forgot to account for water pressure. According to him, the pressure at the very shallow depth I had it at was about 14.7 PSI (or 1 atmosphere), but if I had sunk it deeper to even 1 foot deep, then the differential pressure would be about 0.43 PSI. The point is, if I had sunk it noticeably deeper, then the tin would experience the most adverse of conditions, which is what I was trying to simulate in the original test.
The items here are an Altoids tin, a roll of electrical tape, a tape measure, and a roll of quarters:
Now, in order to get the depth needed, I needed a container to hold water deep enough. What fit the bill was a 5 gallon bucket that is a little over a foot deep:
I put a yellow post-it entitled, “I Am the Stuff…Again” in the bottom of the tin:
On top of that, I weighted down the tin with a small roll of quarters:
Next, the remaining space of the tin is filled with a plastic bag to cushion it:
The tin is then wrapped with electrical tape, in exactly the same way as last time:
So, the bucket is fill with water:
And the tin is inserted into the water:
Now, I wasn’t able to get any visibility of the tin at the bottom of the bucket due to lighting difficulties, so you’ll have to take my word for it.
After it had been in the bottom of that bucket for an hour, I took the tin out:
When unwrapping the last strip of tape along the edge, there are water droplets underneath the tape itself, but this is similar to what happened last time:
The good news is that the inside of the tin is not filled with water:
The underside of the tin had water droplets on it:
Apparently, more water than I had anticipated had seeped in, as you can see by the water droplets on top of the quarters:
Unfortunately, “I Am the Stuff… Again” got completely soaked, so much so that it was easy to tear:
Underneath “I Am the Stuff…Again” is a small pool of water that is noticeably larger than a droplet:
Finally, here is the entire inside of the Altoid tin after it has been dunked in a foot water for an hour:
So, what does this suggest? I think it shows that my reader of mine was correct…water pressure did make all the difference. While the inside of the tin was not flooded, there was significantly more water inside it than there was last test. Perhaps for the next test I should use another sealant on the rim, perhaps candle wax.
If any of you want to repeat this experiment, please do so and leave a comment below. True science is based on repeatability, but it would require other people to follow the same formula.