PLA Get's Brittle
I'm curious whether others have seen what I've seen.
I've noticed that when PLA ages it gets brittle. I've had some spools of PLA that I've had for years and printed with to the end. The very first spool I got with my Prusa I3 Mk2 printed my first prints with that printer, but also was used to print my first prints on my Ender 3 and my Prusa Mini. If you know the release dates of the Mk2 and the Mini you'll know that covered about 4 years. When I'm done with a roll I store it in a large ziplock bag with dessicant to reduce the filament getting wet. This has been mostly successful for me with PLA at least, PETG seems a bit more of a challenge as it gets more stringy with age which I believe is due to moisture.
Anyway, what I've noticed is that while my PLA may not show classic signs of excess moisture as it ages, it does get brittle. I try not to print brittle PLA with my Mini as I've had problems with it feeding, my I3 (now a Mk2.5s) eats it just fine and the prints look pretty good.
I'm curious if others have experienced brittleness in their PLA. I'm also curious if they find the entire roll goes brittle or just sections. I can't say for certain, but it seems like only the outer ring of filament gets brittle and the stuff behind it is more flexible, but I haven't had enough samples to really verify that.
I'd like to hear what others think. Is this a sign of moisture or something else. What do you do when you find your filament brittle?
Cheers
-Bob
Prusa I3 Mk2 kit upgraded to Mk2.5s, Ender3 with many mods, Prusa Mini kit with Bondtech heat break, Prusa I3 Mk3s+ kit
RE: PLA Get's Brittle
For me this is always a sign of too much moisture in the filament. Whenever it breaks by simply unrolling it, I stick in a food dehydrator for 3-4 hours and that fixes it.
RE: PLA Get's Brittle
Interesting, the odd thing is I don't see the other artifacts of moisture like stringing or bubbles, or other surface artifacts on my prints.
Cheers
-Bob
Prusa I3 Mk2 kit upgraded to Mk2.5s, Ender3 with many mods, Prusa Mini kit with Bondtech heat break, Prusa I3 Mk3s+ kit
RE: PLA Get's Brittle
I've only seen one case of wet/old PLA not being printable after a good session in the Ninja Cooker set on dehydrate.
This was a partial spool of FilamentPM silver-gray, (respooled from a 2kg spool by me) apparently the same stuff as the Prusa (non -ment) PLA that's included as a sample with new printers.
I found it in the corner of the spare bedroom, having been exposed to room air for well over a year. It was so brittle that it snapped when unrolling.
I gave it two dehydrate cycles, but on closer inspection it had hairline cracks in it, which caused it to break when used.
I still have another partial 1kg spool from the same 2kg master spool, which is stored in the dry box, and is still perfectly fine.
Look closely at the photo below and you will see the hairline cracks that I am talking about. I just trashed that one.
RE: PLA Get's Brittle
Rumors have it it has something to do with light (either natural or UV). I do not remember anyone doing any tests on that.
It's wet.
Cheerio,
RE: PLA Get's Brittle
Just out of curiosity for a guy that has a MMU with 5 different spools on top of an enclosure and having this same issue what is the fix? I cannot imagine removing each spool every week to dry it and then try to fish all the PLA back through the lines so I can print. That would literally take the fun right out of this as its hard enough every time it cracks and splits apart causing the BEEP BEEP BEEP. Does anyone have any good suggestions to avoid this? are there driers that could be stacked on top of the enclosure or is a different material better? Just looking for an idea other than remove them every week and dry them 🙁
RE:
I don't think I've ever seen a spool which is exposed to room air get contaminated with moisture enough so it will not properly print in only a week.
I have a rack of several spools (PLA, PETg, ABS) above the printer and I've seen some spools sit there for at least a few months and still print just fine. I'll use up the common colors (black, white, gray, etc.) before they get wet enough to cause trouble. For those I don't use that often, I'll keep them in a drybox and not exposed on the rack.
There is one case where I've seen one particular filament get too wet in a very short time, and in this case it depends on the filament type and the brand.
I'm talking about PVA, a water-soluble filament used for soluble supports.
My 'other' printer (Ultimaker S5) has a holder on the rear for two spools, and almost always I have a spool of PVA on it and loaded into extruder 2.
About a year ago I loaded a spool of the Ultimaker name brand PVA and it sat there for maybe 4-5 months or so, exposed to room air before it was used up and always printed fine.
When it started getting toward the end, I reordered, but I noticed that the dealer (Dynamism) then listed a house brand PVA for less than the name brand Ultimaker PVA, so I ordered the house brand. When the Ultimaker PVA ran out, I loaded the Dynamism PVA and at first it printed as expected.
Then in a few weeks I was running a print that used soluble supports and I noticed the tell-tale popping sounds (of wet filament) as the PVA was being extruded as well as the fact that the supports were being poorly printed, as in much weaker and more fragile than they should be.
I aborted the print and put the PVA into the Ninja Cooker overnight. The next morning I reloaded it back into the printer and it printed the supports as expected.
Then in a few weeks it started again. Popping when extruding and poor supports. Rinse-repeat in the Ninja Cooker. Again, perfect supports.
My conclusion from that is that the Dynamism brand of PVA is formulated differently and absorbs environmental humidity far more rapidly than the Ultimaker name brand PVA.
The spool of Dynamism PVA is almost used up, and a while ago I ordered the PolyMaker Polydisolve PVA and I'll try that and see how it works. In the meantime I've been unloading the Dynamism PVA and putting it in one of the dryboxes when not in use.
Another similar data point. The RepRappers yellow PLA seems to be less tolerant of environmental humidity than the other brands/colors of PLA that I usually use. For some reason, that one seems to get brittle more quickly than the other do. That one I'm careful to store in the drybox and just to be sure, I'll cook it in the Ninja Cooker overnight when I have to use it. Contrast that to a spool of Amazon Basics white PLA that's been sitting on the spool rack exposed to room air for at least three months. It prints perfectly and is quite supple.
Just out of curiosity for a guy that has a MMU with 5 different spools on top of an enclosure and having this same issue what is the fix? I cannot imagine removing each spool every week to dry it and then try to fish all the PLA back through the lines so I can print. That would literally take the fun right out of this as its hard enough every time it cracks and splits apart causing the BEEP BEEP BEEP. Does anyone have any good suggestions to avoid this? are there driers that could be stacked on top of the enclosure or is a different material better? Just looking for an idea other than remove them every week and dry them 🙁
RE: PLA Get's Brittle
I should have been a bit clearer, but I have zero issues with any of my PLA printing it just turns really brittle and breaks. This doesn't seem to be one specific color either. I went to print yesterday, and my black color had broken in several different places. It is Hatchbox PLA that I use which the only issue I have is breaking.
I am with JSW. It seems to me that PLA should last a long while in the winter not having issues.
RE: PLA Get's Brittle
Ok I see everyone talking about the Ninja Cooker but no one has mentioned or I have not seen the temperature or the time to put it in there test this out because my PLA is doing the brittle thing, I keep it in another room with proper temperature (I think...lol) is there something else than can help this problem and fix it? Thanks...
If it's brittle dry it at 45/50° for at least six hours. Generally I give every filament two hours each time it's used and don't leave it on the printer if it's not needed.
Cheerio,
RE: PLA Get's Brittle
I usually let them run on dehydrate overnight, ~120F (~48c) and it seems to do the trick.
I've only had one spool that could not be salvaged, and that was due to some small cracks in the filament.
RE: PLA Get's Brittle
Black PLA is substantially immune to UV degradation of its interior due to the black pigment itself. Yet, I've seen it become brittle when very old and never dehydrated.
RE: PLA Get's Brittle
Try printing it at 220C and you will be able to hear it popping and crackling, printing inconsistently and extruding in blobs 😉
As it happens, even relatively moist nylon can be printed at lower temperatures without it foaming... but that means little. Delamination would be an obvious problem of printing PLA in the lower range of temperature and I want my prints strong, so...
RE: PLA Get's Brittle
I currently have a 3 year old PLA spool which I stored at around 25-30 %relH according to my 3 bucks humidity meter.
So not terribly dry.
And it printed just fine the last few days over about 20 printing hours total without additional drying. (Room has 34 %relH atm)
Also, did not get brittle. (It's Prusament Galaxy Black, btw. I over-estimated my consumption a bit and ordered too much ... filament anxiety. 🙃 )
And my carmine red PETG spool (which I don't use too often) also still looks fine after 2 years with the same storage conditions.
But in case of PETG, I would not try to print it right out of the box without further drying.
RE: PLA Get's Brittle
Whenever it breaks by simply unrolling it, I stick in a food dehydrator for 3-4 hours and that fixes it.
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RE: PLA Get's Brittle
You are changing two variables at once by using the food dehydrator. There is good reason to assume the brittleness of the filament is caused by mechanical stress (as tested numerous times, e.g. by PCBurn! here: ). Heating the filament (especially heating it above the glass transition temperature) will release this mechanical stress - yet, in the end, everybody thinks it's the moisture. I have my filaments stored in Samla-based dryboxes, and the PLA often breaks at the transition to the tube or in the part of tube INSIDE the box, too.