Does LEGO float?
On the surface (if you excuse the pun) it seems like an easy question to answer, but perhaps a better question is actually “does LEGO float in all cases?”. Suddenly this is a more interesting question, and one I was quite happy to test. To do this, I enlisted in the help of Newbury’s J.B. Watt to test this question. She brought along Billy and Buster (the Test Dummy) to help.
Ever wondered what makes some things float and others sink? A leaf floats on the water because it’s light, but super tankers and ships can weight many, many tonnes and yet they seem to float quite easily?
So, the first thing to think about is an object’s density. Heavy things sink, light things float. Things can be made to seem lighter in water, by reducing their density; this can be achieved by making them hollow. This reduction in density introduces the next factor; that of buoyancy. Buoyancy is a bit like gravity, but where gravity will pull things down, buoyancy will make them float. A “positively” buoyant thing will float (or rise), a “negatively” buoyant thing will sink; finally, a “neutrally” buoyant thing will neither float nor sink.
But for our experiments, there is another factor to consider; that of the Meniscus layer on the water surface. This is a layer of tension, which acts like a sort of barrier. It’s not very tough, but it allows the water to hold together; this is why water forms droplets when you splash it about. For very light things, this water tension can also provide the difference between a thing floating or sinking. Some animals, like the Water Boatmen, use this tension layer to walk (or skate) across the water’s surface.
So, we know light things float, heavy things sink and if the thing is pointy enough (with enough weight) it will either break through the water surface or not. Okay, onto the tests!
The testing area
Much as I have a lovely pond for floating LEGO in, it isn’t very clean and there’s a much bigger risk that I would drop and sink something, and I didn’t want that to be my phone or the LEGO. So, I found a clear glass dish that we filled with water. We could then control how far the subjects drifted (or sank).
The tests themselves will consist of effectively two parts; first, we’ll float the LEGO on its own and then we’ll add Buster to see what impact that has. I’ll make an observation here that Billy got very into testing and sort of forgot about photography, so there will be some pictures that don’t show all the tests; there are also photos that looked okay on the phone (or so he said), but were out of focus when I looked at them more calmly afterwards. But you’ll get the idea anyway.
Control test and boats!
The next test that I wanted to try was to see if Buster floated or sank when I put him in water. The result was … he sort of floated. As we can see from the side, quite a lot of him is underwater. There is obviously some buoyancy to him (after all, his body does have an air cavity, as do his legs, and I didn’t try tapping him to see if he would then rise, but I’m going to say that yes, LEGO minifigures float!
The next test was to see how Buster behaved if we put a rubber ring around him. I had hoped that he would float upright, but no…
So, here’s when the testing started. If you have ever tried to build a brick boat and float it, chances are that it didn’t float at all successfully. So, for these tests, I used a 2×4 plate and a 2×4 brick.
The results were as expected. Because the brick and the plate have a hollowed underside, they do have some buoyancy. The plate is so light that the meniscus also plays a part in keeping the LEGO buoyant:
Other floaty things
First, the float tests:
Oops! Hang on! Iceberg ahead!
I decided to expand the test on the kayak, removing the oars from Buster. He floated for a bit; then…
The final test
The final test was to use LEGO bricks again, but this time as a dinghy construction. As soon as I put the build in the water, I could feel the buoyancy push back; so, I added all the figures:
An obvious success, and we can see why. Each of the four 2×8 bricks has air pockets providing buoyancy and this is distributed over a wider area, making it very stable indeed!
All good science experiments should have a conclusion, and this is no different. If we ask “Does LEGO float” the answer is possibly. For the more precise question, “Does LEGO float in all cases”, the answer is no.
I would also note that even when LEGO does float, it doesn’t always do so in a way that would be expected in a “real world” scenario and can be rubbish for photography! I was also really pleased that I didn’t do the umbrella test in the pond either!
Don’t forget to check out our other article here about LEGO and water!