PLA is the most popular 3D printing material, but people question its durability, especially when wet. One question people ask is if PLA breaks down in water, and if it does, how fast does it decompose?
With standard water and no extra heat, PLA should last decades in water since PLA requires special conditions to break down or degrade. Many people use PLA in aquariums, bathtubs, or pools without issues. Tests have been run with PLA underwater and it has lasted for years.
It should be the same with salt water also. PLA doesn’t dissolve or degrade in water like some may think.
This is the basic answer but there’s more information that you’ll want to know, so keep on reading.
Does PLA Break Down in Water? How Long Will PLA Last in Water?
PLA does not completely break down or decompose unless the water temperature is sustained above 50°C with presence of particular enzymes for biological reaction where this takes a duration of about 6 months for it to break down.
Many user experiments have shown that normal PLA doesn’t break down in the water. They have shown that PLA can indeed quickly fracture into microparticles under hot water and extremely harsh temperatures after a long time.
A user observed that a soap tray he had from PLA had stayed in the shower for about two years without any signs of decay. This shows just how long PLA can withstand water without breaking down.
Another user made a garbage disposal strainer stopper out of a PLA brand that was strong enough to allow sink water to drain, with frequent dumping of boiling water for over a year.
One experiment showed the effects of four different environments on a 3D Benchy print. One in water, soil, open sunlight, and his working desk for 2 years. The test results showed no difference in the strength of the material for each environment.
As found out through many tests, it takes PLA to be in water for several years for it to show any sign of degradation.
How Quickly Does PLA Degrade/Deteriorate?
Polylactic Acid (PLA) is often promoted as biodegradable. However, it degrades and wears out a little when fully submerged in water and for this to happen it may take up to 2 years. It won’t deteriorate under normal conditions.
PLA printed materials are known to last over 15 years in open sunlight unless it exposed to mechanical pressure.
In an experiment, a user tested various filaments using test disks of different dimensions, 0.3-2mm thickness, 100% infill with the outer ring being 2-3mm with 10% infill.
He tested 7 different types of filaments.
This included atomic PLA and Silk PLA, placed in a hot water bath of about 70°C in a polystyrene plastic tub using an immersion heater.
The filaments immediately flexed out of shape when inserted in the water since the water temperature was above the glass temperature of PLA.
PLA filament was observed to flake at the end of the 4 days while most became brittle, could be broken with little force applied, and easily crumble when broken by hand.
Check out the video below.
Prints made from PLA filament that has absorbed water before printing may tend to swell up or become brittle. This is because PLA is hygroscopic or absorbs moisture from the environment.
This moisture can cause printing issues such as bubbling from the heat of the nozzle affecting the moisture, leading to PLA degrading faster.
Is PLA Bad for the Environment or Environmentally Friendly?
Compared to other filaments, PLA is relatively good for the environment, but it can’t be recycled or reused efficiently to be environmentally friendly.I consider PLA to be a little bit more environmental friendly than other filaments such as ABS filament which is a petroleum-based thermoplastic.
This is because PLA filament is a bioplastic made using non-toxic raw materials such as starch extracted from natural materials.
When most people start printing they learn about PLA as biodegradable or filaments often tagged as plant-based environmentally friendly plastic.
This is mentioned in many filament comparisons, primer, and tutorial stating that PLA is great because it is biodegradable, but it isn’t necessarily environmentally friendly as a whole.
PLA is relatively easier to recycle at specialized facilities compared to other filaments. When it comes to pure PLA, it can actually be composted in industrial composting systems.
In terms of reusing PLA so it isn’t thrown away, the main thing you can do is to melt the plastic or shred it into small pellets that can be used to create new filaments.
Many companies specialize in doing this, as well as selling the machines that help users to create their own filaments. It’s possible to purchase “greener” filament, but these may be more costly or be structurally weaker than your usual PLA filaments.
One user mentioned that his local waste station doesn’t accept PLA, but you can usually find a place nearby that can handle it.
You can also think about how much less plastic is bought and used as a result of fixing things with 3D printing that you might have otherwise thrown away and rebought.
Many people are now choosing to reduce their plastic packaging by purchasing just the filament itself and having a reusable spool. The main concepts to follow with 3D printing in terms of being environmentally friendly is to Reduce, Reuse & Recycle.
The biggest impact on the environment will be to reduce the usage of plastic overall, which 3D printing is helping with.
Is PLA Compostable at Home?
PLA is not really compostable at home unless you have a proper specialized machine. A standard backyard composter is probably not going to work to compost PLA.Rather PLA will break down in an industrial composter which gets to much higher temperatures than a home composter unit.
Although PLA prints are known to degrade when exposed to harsh environments over time, it is hard to get rid of PLA since it is only compostable under very precise conditions.
This is because it needs the presence of a biological process, a sustained high temperature, and takes a long time which are not conducive for a home unit.
It has been found that raw PLA materials can be biodegradable more than petroleum-derived polymers such as ABS, but not by much.
A user noted to have learned that a compost unit must reach a sustained 60°C (140°F) to effectually decompose PLA. This temperature is achieved in commercial composting units operations but is difficult to achieve at home.
Here is a video that explains more on the PLA biodegradability.
A YouTube channel called Brothers Make offer various ways to recycle and re-use PLA leftover materials for those who may opt for this option to utilize PLA waste in making different objects for various use.
People suggest that one can melt down PLA at 180°C to make a big slab or a cylinder, and use it as stock for lathe or CNC millwork.
Is PLA Plus Waterproof?
PLA Plus can be waterproof when 3D printed with a properly calibrated 3D printer and a large wall thickness. The filament itself can hold water without leaking, but you’ll have to use the right settings and have a good 3D printed container. PLA Plus itself
Here are some tips you can follow to make PLA+ filament waterproof
- Adding more perimeters for a print
- Over extruding filament when printing
- Printing thick layers by using a larger diameter nozzle
- Coat the print with epoxy or resin