Is PLA for 3D printing really biodegradable? I’ve buried and drowned Benchy for 2 years to find out!


Two years ago, before this channel even existed, I’ve
printed four Benchies to see what would happen if I put them in water or burry them in my backyard. I know that isn’t the most scientific test, so before we get
to that, I’ve printed these hooks that are perfect for testing. You might have seen them before? The famous test hooks created by Stefan from CNC Kitchen! What’s more, he’s agreed to test the hooks for me, so the results should be much more reliable. He’ll test one set now as a baseline for comparison. I’ll put the hooks in same conditions as the Benchies and
then wait one year. Now all I have to do is get this to him so he can test the
first batch. [doors sliding] [airplane engine starting] [wind howling] PLA is often promoted as being biodegradable and therefore
environmentally friendly. So if you frequent any 3D printing forums, you’re bound to
find people claiming that you shouldn’t use PLA for fish tanks or outdoors,
because it will degrade before this video is over. But is all of that actually true? Well, I’ve decided to find
out! Two years ago, I’ve printed four Benchies to see what would
happen under different conditions. The first Benchy was submerged in water. The second one was buried in my backyard. The third one was left outside to the elements; sun, rain,
freezing temperatures, you name it. The final Benchy was left on my desk so that I have
something to compare all the others to. So why Benchy? Well, what better model than the one that’s been torturing
our printers for so many years now? Now, before you comment that I should have used water from a
lake that has bacteria in it or something, I’ll explain in a minute why it wouldn’t have made any
difference. As expected, the Benchy on my desk remained exactly the
same. Looks the same and feels the same. I’ll break off the chimney, just to see how much force I
need so that I can compare it with others. This one looks the same as well, which is a bit surprising. I wasn’t really expecting much, but I thought at least the
color would fade a little. I’d say it took the same amount of force as before. Ok, let’s check out the buried one next. [digging] Well, at first glance, it looks the same. Doesn’t feel brittle and I can’t see any surface
deterioration. Let’s bring it inside and wash it so we can take a closer
look. Everything feels solid and the chimney was just as hard to
break off as the first one. It seems like being buried underground didn’t have any
affect whatsoever. To be honest, this was the one I was sure would show at
least some signs of degradation. As it is, I can’t tell any difference between the two. Let’s check the final one that I’ve kept in the jar filled
with water. Well, it doesn’t look any different… No weird smell or
anything… Seems to be just as solid as the other two. After letting it dry out for a few hours, let’s compare the
weight to see if it absorbed water. Well, the weight is slightly different between all four of
them, but as I don’t have their original values, that doesn’t really help us much. That’s something that I’ll
fix with the new test. It’s funny how moisture can affect filament spools, but if
you let it swim in water for years, it doesn’t do anything. Before you say that I’ve only used tap water instead of
something more potent, here’s why it wouldn’t have mattered. A few years ago, researchers in Germany conducted a test
aimed specifically at trying to determine how saltwater would affect
biodegradable plastic. Looking at the results for PLA, we can see there was no
significant change after an entire year of being submerged in saltwater. This confirms what my test of two years showed as well. But they did use distilled water and added salt to it, so
who knows, maybe it wasn’t strong enough? Well, in another study, researches from Japan went even
further. Instead of using saltwater, they used actual seawater from
the Pacific ocean. They also tested both tensile strength and Young’s module. Even then, the results reached a similar conclusion; after
being submerged in seawater for 3 months, PLA showed no significant difference in weight, tensile
strength or Young’s module. As I’ve mentioned at the beginning, I’ll repeat my test
again with the hooks and back it with some numbers. I’ll explain more at the end of this video. Look at almost any brand of filament and you’ll see a claim
that PLA is biodegradable. So if PLA really is biodegradable, why did all the Benchies
stay the same after 2 years, and scientific research showed the same results? Well, as with most things in life, it’s much more
complicated once you look at the details. In reality, PLA is biodegradable only under very specific
conditions. The enzymes that could break it down are virtually
non-existent in nature. Throw away PLA in the forest, and it will stay there,
unchanged, for decades. Throwing it into the ocean doesn’t work either, as we’ve
seen with the seawater test. So if PLA doesn’t degrade naturally, then how else? That brings me to the main issue with PLA – it’s only
biodegradable in composting facilities where it must be constantly heated at around 60’Celsius, within certain, high oxygen levels and with correct micro-organisms present. Even then, it can still take over 6 months before it’s fully
degraded. These conditions can only be achieved in dedicated recycling
facilities, which brings me to the second issue with PLA. In practice, PLA is almost never recycled, as it simply
takes too long and it cannot be mixed with other plastics. This means that recycling facilities won’t bother with it,
but instead will either incinerate it, or even more likely, ship it off to a landfill. We only have to look at Germany to see how hopeless the
situation is. Germany is the world leader when it comes to recycling, yet
of nearly 1-thousand composting plants here, less than 5% are actually capable of composting PLA. And even for those that could, PLA would have to be
collected separately, as it cannot be mixed with other
plastics. When was the last time you saw a dedicated collection bin
for PLA? What actually happens is that PLA simply gets dumped in the
landfill, and because conditions there are far from ideal in terms of
composting, it will stay buried for centuries. So yes, while PLA is biodegradable in theory, it’s anything
but in reality. This brings me to my last issue with PLA; manufacturers are
well aware that PLA doesn’t end up being degraded or recycled, yet they’re quick to label it as
eco friendly. They’re happy to cite how their plastic is biodegradable
under this or that standard, while on the other hand, barely any composting facility is capable of achieving those
standards, and even those that can are doing their best to avoid it. This is far from only being limited to PLA filaments; it’s the same story with containers, cups and bags, which
are all labeled as biodegradable. This produces a false sense of responsibility, as people are
quick to throw biodegradable plastic away, thinking it will actually end up, well, biodegraded. So you see, it’s not as simple as it seems. While PLA is certainly better than ABS, there’s no easy
solution. PLA is biodegradable on paper, yet most of it ends up in a
landfill. There’s one service aimed at recycling 3D printed waste –
ProjectPLA. Basically, you pay for an empty box, fill it with failed
prints and send it back. They then grind it down and ship it to facilities that can
actually handle PLA. It’s a very worthwhile project and I encourage you to check
it out. So I guess what I’m trying to say is, don’t print useless
stuff that you don’t really need, PLA is far from being eco-friendly. As I’ve mentioned earlier, I’d like to repeat this
experiment in a better way. When I first thought of the test, two years ago, this
channel didn’t exist yet, so I didn’t prepare for it as I normally would. Now that Stefan has agreed to test the hooks for me, I’ve
printed out a bunch of them. As with the Benchies, I’ll leave them outside, in water,
burried and on my desk. Just to eliminate any variations, I’ll use 6 hooks for each
part, so we’ll actually have 24 hooks in total, plus the 6 that Stefan will test now. I’ve took exact measurements and weight for every hook, so we’ll also be able to see if they shrink or lose weight
over time. Based on everything I’ve seen so far, I’m not really
expecting much, but at least we’ll have some numbers to back it up next
year. And with that, thank you for watching and I’ll see you soon.

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