Water absorbtion

[BrokenBiker]

Does PLA absorb water like PETG?

I've started to notice some stringing on my 2 open spools of PETG, the other 4 spools are still sealed at the moment but I've just ordered 10 spools of pla and 3 silk PLA so just wondering if I need to make some sort of dry storage for them or just the petg?

 

[Pete.]

Yes most definitely. If you leave a spool on your printer for a long while the exposed length will mysteriously snap. Pull a few turns off the spool and the rest will print without breaking.

 

[Bladevane]

Sorry to disagree with @pete but I do not believe PLA does absorb water like PETG. Whilst I agree with the snapping issue I have not experienced the popping noise of the PLA filament going through the extruder which is indicative of moisture absorption. Mind you, we don’t live in a swamp or an area of high humidity. So @BrokenBiker all I can say is don’t get hung up about drying PLA before using it. Try it and see. If you get popping as it heats up and extrudes then it needs drying.

 

[Pete.]

You might be right when I first had thw snapping problem after leavi g my printer standing for several months I did a search on it and that way the reason given. I didn't look any further into it than that.

 

[BrokenBiker]

Cheers for that, I'll be drying my 2 open spools of PETG then storing them in a box with some silica but won't worry about the silica for the pla

 

[m_c]

PLA tends to go brittle as it ages, but doesn't really absorb enough moisture to be an issue.
I've had brand new reels of PLA that pretty much just shattered as it was old stock.
However there is quite a wide range of PLA mixes, some of which are more susceptible to issues.

I used a couple rolls of Extrudr PLA this week that had been lying around for 6 months, and they printed as goog as the day they were opened.

PETG on the otherhand will fairly quickly absorb enough moisture that it affects print quality, but it's a more consistent/stable material so will print fine once dried.
I keep all my opened PETG reels in sealed boxes with desiccant pouches and moisture meters to keep them as dry as possible.
It's worth noting that even brand new sealed PETG is likely to be fairly damp, so it's always worth drying new reels before use.

 

[MattF]

It's worth noting that even brand new sealed PETG is likely to be fairly damp, so it's always worth drying new reels before use.

I've noted that too. Now, they go in the drier straight from the packet.

 

[Dapph2]

Stick a spool in a warm airing cupboard for a few days and report back ? If it works always store started spools in a zip-lock bag with a few desiccant packs inside the bag ?
In my enclosure cabinet there has been a spool on the Prusa for 2 years or more .

When I get back to playing I'll put he cabinet heater ( 2x 7 watt CFL's ) on for three or four days to dry everything out& bring the temperature up to around 70 oF

 

[ukracer]

Yes most definitely. If you leave a spool on your printer for a long while the exposed length will mysteriously snap. Pull a few turns off the spool and the rest will print without breaking.

I thought that was only me who found this happening.

 

[m_c]

I've noted that too. Now, they go in the drier straight from the packet.

It's because of how the filament is extruded.
They typically use water cooling, and despite being dried after cooling, due to the process times there will inevitably be some water that doesn't get dried off, and the little desiccant pouch packed with the sealed reel isn't really enough to absorb all the remaining moisture.

 

[Spuddevans]

I've found that Silk PLA does not store well, even when stored in vac-pac bags with dessicant. Every single roll of Silk PLA (different brands) I've had, has gone brittle after a month or so and ends up snapping in the printer's feed-tubes. I've stopped using Silk, if I absolutely have to use silk, I try to use it up within a month.
Tim

 

[Dapph2]

I've found that Silk PLA does not store well, even when stored in vac-pac bags with dessicant. Every single roll of Silk PLA (different brands) I've had, has gone brittle after a month or so and ends up snapping in the printer's feed-tubes. I've stopped using Silk, if I absolutely have to use silk, I try to use it up within a month.
Tim

But does it go brittle in what you printed ???

 

[BrokenBiker]

I've found that Silk PLA does not store well, even when stored in vac-pac bags with dessicant. Every single roll of Silk PLA (different brands) I've had, has gone brittle after a month or so and ends up snapping in the printer's feed-tubes. I've stopped using Silk, if I absolutely have to use silk, I try to use it up within a month.
Tim

The only prints that need to be done with this silk will be knocked out over a couple of days, can't see anything else I need the copper for, and don't plan on opening the other 2 til they are needed, more a nice to have sort of thing

 

[Spuddevans]

But does it go brittle in what you printed ???

Good question, but I can't answer as every time I've tried to print with it, it snaps in the feed tubes and so the print is abandoned! However the stuff I've printed when the Silk-PLA is freshly opened, I haven't noticed any additional brittle-ness over time (although all the Silk-printed bits I've done are all decorational rather than practical or structural prints )