Eco-friendly polymer for outdoor plant pot  

You might try BioPro from 3DTomorrow.   I have been testing it for the last 6 months as a low grade engineering filament and I just bought another three spools ...

OK, only 6 months but it has stood up well to heat as advertised, it's tough and so far ultraviolet light damage is undetectable.

https://3dtomorrow.com/product/3dtomorrow-biopro-3d-printer-filament-1kg-1-75mm/

Having said that I don't consider printing plant pots a good idea, far better to repurpose or adapt some other container that would otherwise have been dicarded after a single use. 

Cheerio,

RE: Eco-friendly polymer for outdoor plant pot

Thanks for the advice, I'll try the BioPro PLA out.

It's a experimental invention I'm printing, so I'd really need to 3D print it rather than repurposing other items.

I wonder how they achieve those PETG-like properties. I think I will need to make my own filament, as part of the product needs a certain degree of porosity, which I must calibrate myself through trial and error. So I would be interested in knowing how they achieve these qualities, since it would be much better for the environment to build the product from PLA.

Most of the time 3D printed containers *are* porus.  The actions needed to make waterproof parts are recurring questions here.  Varying the number of perimeters and printing temperatures will give you a range of qualities.

When I finished my first printer build I followed the tradition, long gone now, of making the first print a shot 'glass' and toasting the successful build in strong liquor.  It had to be downed in one as a measure of fine single malt would leak away through the print in under 30 seconds.

Cheerio,

RE: Eco-friendly polymer for outdoor plant pot

When I finished my first printer build I followed the tradition, long gone now, of making the first print a shot 'glass' and toasting the successful build in strong liquor.  It had to be downed in one as a measure of fine single malt would leak away through the print in under 30 seconds.

Cheers to that! 🍻 

RE:

You're worrying me!

I'm aware unwanted porosity is a common issue. However, I'd read into it a bit and it seemed that by adjusting the number of perimeters, layer height, temperatures, materials etc. it would be possible to get a water-tight print. Is this wrong? If I print transparent PETG with 4 perimeters and tweak the layer height down a bit, would this not work?

The way I saw it, my task was to identify the best material, with the best properties for my task, and then to perfect a 3MF file that got the balance right between structural integrity and speed.

Once impermeability was achieved, my plan was to reintroduce permeability in a controlled manner, through the addition of some additive to the pellets, e.g. some ratio of fine salt which would dissolve in the pellet filament extruder's water bath upon spooling. I'd be trying to emulate the porosity of unglazed terracotta. 

I'd be wary of adding crystals or powders to filament as they are liable to abrade the nozzle or even jam.  Have you thought of selective use of soluble filaments, PVA for example, to make 3D channels without the inherent tendency for extrusions to close narrow gaps?

By using modifiers you should be able to make parts of a print differently watertight/permeable.

See:

https://blog.prusa3d.com/watertight-3d-printing-pt1-vases-cups-and-other-open-models_48949/

https://blog.prusa3d.com/watertight-3d-printing-part-2_53638/

Cheerio,

RE:

Thanks for the links. They say 3D printed gaskets don't work. That sucks. I had planned on using TPU-printed O-rings...

Soluble filaments are interesting. But, I imagine the pellets would always be too large to have the subtle effect I am looking for in reproducing unglazed terracotta's porosity. That's why I considered incorporating different ratios of fine salt and testing which ratio works best.

Re the issue you describe with salt in the nozzle: Couldn't a fancier filament extruder nozzle be used for the purposes of extruding an abrasive pellet mixture into filament? As soon as the filament is extruding, it would enter a cold water bath, which should immediately dissolve most of the salt, so that no modifications would be necessary on the nozzles of the 3D printers themselves. Intuitively, it doesn't strike me as an insurmountable issue, but there might be something I am overlooking.

RE:

They say 3D printed gaskets don't work. That sucks. I had planned on using TPU-printed O-rings...

O rings are available in a huge range of sizes, pick one and design the part to fit.

Soluble filaments are interesting. But, I imagine the pellets would always be too large to have the subtle effect I am looking for in reproducing unglazed terracotta's porosity. That's why I considered incorporating different ratios of fine salt and testing which ratio works best.

You can grind the solubles to a flour if you wish - go slow and keep cool.

 Couldn't a fancier filament extruder nozzle be used for the purposes of extruding an abrasive pellet mixture into filament? As soon as the filament is extruding,

You would definitely need a hardened nozzle.

3D prints are porous because of wicking through the printed matrix.  Try experimenting with a few print settings and see if you can get acceptable results by changing slicing parameters.

If this is to go outdoors you might need to test in the freezer too.

Cheerio,

RE: Eco-friendly polymer for outdoor plant pot

Biodegradable Filaments are largely a marketing ploy. Even PLA needs industrial composting conditions to degrade, which you won't find in nature. Those materials which are suitable for outdoor usage are usually even less biodegradable, or not at all. Non of them are porous by themselves to my knowledge. 

The problem for PLA outdoors is its modest heat stability which can lead to deformation in the sun on a hot day, at least if you have some reflections involved etc but also that UV light is making the material brittle. Good materials for outdoor use I know of are PETG, PCTG, Nylon, ASA or Durabio. Nylon is the most challenging to print of those. None of them are porous, in deed PETG, PCTG and Durabio are materials very well suited for printing watertight objects. 

If you have a filament extruder you can experiment with soluble infill like fine salt etc, as said above, the use of a hardened nozzle would be a good idea then. I would also think about maybe using a larger nozzle size,  maybe 0.5 or 0.6 mm, to reduce the risk of clogging. 

An alternative option would be to to print a casting form and cast your object. I am not an expert on that but you can use materials there which can't be printed and the choice for porous or degradable materials is probably greater using that method.