Want to make what are usually net cups for plants grown hydroponically but use them for seed starting. The cups are actually too shallow for good root development for plants you are going to prow for growing in dirt.
They will sit in a tray that is filled to about 1/4 to 1/2 inch deep with water until it evaporates and then will be refilled. The bottom soil will always be damp.
Couldn’t find good info on this, Figure I was not using the right search terms, so I thought I’d ask here.
I believe the search term you’re looking for is this
‘water resistant fdm filament - Google Search’
Which yields the same 3 filaments in most of the articles, PETG, ASA and ABS. Mention for Nylon and PP are also included but I would consider those filaments as exotics due to their inherent special needs.
I can say this, I created a series of self draining weighted soap dishes for my shower and bathrooms. I was sick and tired of cleaning up soap scum and the self draining solved that. I used marble colored PETG for appearance purposes and it has been working very well for the last nine months of daily use. I specifically was looking for problems with water absorption and leakage. So far, the weight of the soap dishes hasn’t changed over the last few months that I checked and that gives me confidence that water is not being retained.
I should note that I did not perform a leakage test so if your intent is to provide water containment, you may want to test your print.
Nope, the water containment is done by the tray they’re sitting in.
All filament suck up moisture and water to some degree.
As a container you want something airtight.
The usual candidates were already were already mentioned and they do well with exposure to water.
What about your plants though ?
None of the cheaply available filaments are food rated, same for drinking water use.
That is not just due to risk of plastic getting loose but mostly due to those plastic leaching out chemicals.
I had VERY mixed result with using printed models for plant use and would never dare using them in my fish tank…
Be careful with a statement like that. True, filament, some filaments that is, are hydroscopic. However, printed plastic once extruded out of a nozzle changes properties once it has reached the glass transition phase.
Think of it in some ways like sand. When sand is just silica quartz, it has a lot of air bound in the cracked crystals. However, once it is melted and then cooled quickly, it becomes a solid transparent product. (Mostly that is, pure quartz is normally not totally clear unless chemicals are added.) Something similar happens to filament. After it prints, it is no longer hydroscopic because it has transformed into something more akin to glass.
I bought my printer last fall–September, I think it was. Two of the first items I printed included a Tub Drain catcher and a Sink Drain catcher. I used Silk Silver PLA. They show no signs of shrinkage or swelling. They fit the same now as the day I started using them. The one in tub gets used 1-2 times daily (shower). The one in the sink gets used about 6-8 times a day (washing my hands).
If I had the need to do any pot-printing for plants, I wouldn’t hesitate to use PLA. It’s easy, and very forgiving. From my experience, it’s got to last longer than the cheap pots from the store that look like they’re made of Plaster of Paris or the like.
Of you are correct by stating filament is far more prone to the affects of water or just humidity than printed parts.
But just to be fair:
When I print something and note the weight once cleaned up the part SHOULD still have the exact same weight after being submerged for a few days or more and dried in air for a few hours.
For most filaments this is not the case and the parts are slightly more in weight.
Not by a bunch of milligrams but still.
PLA for example resists a lot of chemicals, including most polar and non-polar solvents normal people might have around.
But it is also biodegradable…
While the actual and long term contact with water is no big deal, what might in the water can…
I printed a little tank ornament for a gold fish tank a friend had many years ago.
Lost most of the colour within a few weeks but other than that seemed fine.
Until it was time for a proper cleaning of the tank.
The PLA had turned rather ‘soft’, almost like semi soaked clay you left outside to end with a dry and hard surface.
With a bit of pressure it all crumbled…
Yes, it might have been crappy filament but I noticed similar issues with PLA used on my motorbike and friends boat.
As said, probably not as much the actual water but what comes with it…
PETG is still my favourite here.
Nylon if there is no way around it because I just try avoiding having to use it.
A major issue I found many noobs struggle with is getting the model actually WATER PROOF.
This is especially true for things that are intended to be used submerged or get fully submerged more often than what they are dry.
It is very easy for water to be pushed into the infill or other voids even if the model only goes bucket deep…
Once in though it is very hard to get it out…
As the topic is about what is usable for water contact I just say to stay away from PLA and to consider PETG, PE or Nylon instead.
like @Olias mentioned above, PETG is a good choice for water contact as it doesn’t need special printing conditions and is as cheap as filaments get. I have also been using a petg soap holder without any problems for months now.