PETG became soft  

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prusanewuser
(@prusanewuser)
Honorable Member

Hi, I was using PETG in the summer and after that, I put it inside the original sealed bag with two large packs of silica. When I took it out, how come it became soft?

Will the resulting prints be less strong and easier to break compared with a new unopened spool? 

This topic was modified 3 months ago by prusanewuser
Posted : 11/01/2021 3:58 am
loadinglevelone
(@loadinglevelone)
Trusted Member

Most of my PETG is fairly soft. Whenever I have PETG with a lot of moisure, it becomes hard and brittle. 
I would think that your PETG is fine. Have you tried printing with it?

This post was modified 3 months ago by loadinglevelone
My printers: Mk3s / Mk3s clone with +upgrdaes (you know SPinda and all that good stuff) / Mini+ / Ender 3 v2...
Posted : 11/01/2021 10:27 am
prusanewuser
(@prusanewuser)
Honorable Member

@loadinglevelone

Not yet. Somewhere I read that PETG absorbs moisture quickly. Is that really true? If I make something out of PETG, will it absorb moisture over time and loose its strength?

Posted : 11/01/2021 2:52 pm
towlerg
(@towlerg)
Prominent Member

Yes PETG absorbs moisture as do pretty much all materials used for 3d printing, Nylon is very hygroscopic, PLA not so much. Personally I live in a area with high humidity and low temperatures (west coast of Ireland) and I regularly leave PETG on the printer continuously. If your filament is "wet" you may hear a popping sound as the water boils off in the hotend.

This post was modified 3 months ago by towlerg
Posted : 11/01/2021 6:46 pm
prusanewuser
(@prusanewuser)
Honorable Member

@towlerg

Thanks. For this filament, I have not heard of popping sound.

Since pretty much all materials used in 3D printing absorb moisture, does that mean prints made using PETG or PLA cannot be as strong as new over time? 

This post was modified 3 months ago by prusanewuser
Posted : 11/01/2021 7:15 pm
Hooch
(@hooch)
Trusted Member
Posted by: @prusanewuser

Since pretty much all materials used in 3D printing absorb moisture, does that mean prints made using PETG or PLA cannot be as strong as new over time? 

Yes, they do absorb moisture but it has no noticeable effect on printed parts. I did test. I printed 10 "strenght" tests and put then in different enviroents for 1 year.

  • In bag with silica (0% moisture).
  • Submerged in water.
  • Submerged in salt water.
  • 50cm underground in wet soil.
  • Inside ice cube in freezer
  • And few more...

Generally they absorbed max of 1% of water by weight. There was no measurable difference in strength. So... Do not worry about humidity after you printed your parts. (But do keep filament dry to make better prints).

Posted : 12/01/2021 8:25 am
loadinglevelone
(@loadinglevelone)
Trusted Member

I've had PETG open on shelf for months which still prints flawlessly. I try to keep my filaments in a sealed bag with silica if I can, but honestly I've only ever had to dry a spool of filament once because of moisture and printing problems.

If you do a google search you'll be overwhelmed with filament moisture tips, claiming a dry-box is must-have and tutorials on DIY filament dryers. I've never bothered with any of that. At least where I live - moisture is not a problem.

This post was modified 3 months ago by loadinglevelone
My printers: Mk3s / Mk3s clone with +upgrdaes (you know SPinda and all that good stuff) / Mini+ / Ender 3 v2...
Posted : 12/01/2021 8:45 am
Hooch
(@hooch)
Trusted Member

@loadinglevelone

It is all about where you live. There are parts of the world where moisture is so high it WILL kill your filament. I keep mine in box with 1kg of silica gel in a sock. I keep filament in box anyway. So adding 1kg silica gel (about $5) is not a problem to just be safe.

Posted : 12/01/2021 9:42 am
towlerg
(@towlerg)
Prominent Member

"Since pretty much all materials used in 3D printing absorb moisture, does that mean prints made using PETG or PLA cannot be as strong as new over time? " Certainly any moisture will boil off in the hotend. The other effect of "wet" filament is a rough surface finish.

 

According to Met Éireann humidity was 99%, I have no idea what that means.

Posted : 12/01/2021 11:11 am
cwbullet
(@cwbullet)
Illustrious Member
loadinglevelone
(@loadinglevelone)
Trusted Member

@hooch

Yeah, I know. I live in Norway where air humidity is no problem whatsoever. 
At the time of writing the hygrometer on my wall reads 22% at the moment. That's dry! 🙂

My printers: Mk3s / Mk3s clone with +upgrdaes (you know SPinda and all that good stuff) / Mini+ / Ender 3 v2...
Posted : 12/01/2021 11:39 am
loadinglevelone
(@loadinglevelone)
Trusted Member
Posted by: @towlerg

According to Met Éireann humidity was 99%, I have no idea what that means.

From google: A relative humidity of 99% means that the air is holding 99% of the water vapor it is capable of holding at that temperature, not that the air is 99% water. The air may actually contain only about 5% or so of moisture even in the most humid condition.

I believe that recommended normal indoor household humidity levels is somewhere around 30-50%.

This post was modified 3 months ago 2 times by loadinglevelone
My printers: Mk3s / Mk3s clone with +upgrdaes (you know SPinda and all that good stuff) / Mini+ / Ender 3 v2...
Posted : 12/01/2021 11:43 am
prusanewuser
(@prusanewuser)
Honorable Member

@hooch   Thanks for the interesting test. So we need to pay more attention to humidity only before the filaments are used? What about PLA? What materials did you use in your strength test?

 

How do I know my place has humidity high enough that I need to be concerned about its effects on filament?

Posted : 12/01/2021 2:45 pm
towlerg
(@towlerg)
Prominent Member

@loadinglevelone

That makes sense. It seemed intuitive that there was some relationship between temp and humidity.

Posted : 12/01/2021 2:49 pm
loadinglevelone
(@loadinglevelone)
Trusted Member
Posted by: @prusanewuser

How do I know my place has humidity high enough that I need to be concerned about its effects on filament?

Cheap digital hygrometers can be bought for a couple of bucks from ebay or aliexpress. 
I have a few of these, which I place among my filament.

There are lot of stl files out there which allows you to mount them in the filament spool, or on the printer.
Here's a few of them: 
https://www.prusaprinters.org/search/prints?q=humidity

This post was modified 3 months ago 3 times by loadinglevelone
My printers: Mk3s / Mk3s clone with +upgrdaes (you know SPinda and all that good stuff) / Mini+ / Ender 3 v2...
Posted : 12/01/2021 3:07 pm
prusanewuser
(@prusanewuser)
Honorable Member

Speaking of dry-box, what is the different between putting PLA/PETG/BVOH naked inside the printer cabinet only during use vs. putting them in a PolyBox 2 during use?

Posted : 13/01/2021 12:07 am
cwbullet
(@cwbullet)
Illustrious Member

@prusanewuser

A dry box would have to less humid even with the heat of the printer in the enclosure.  

--------------------
Chuck H
3D Printer Review Blog...
Posted : 13/01/2021 2:20 am
prusanewuser
(@prusanewuser)
Honorable Member
Posted by: @cwbullet

@prusanewuser

A dry box would have to less humid even with the heat of the printer in the enclosure.  

Do you mean during the print job, it is still better putting the filaments inside a dry box located outside the enclosure than just putting them naked in the enclosure?

Posted : 13/01/2021 2:54 am
cwbullet
(@cwbullet)
Illustrious Member

@prusanewuser

That is my opinion.  I think a dry box is gonna keep it dryer unless your enclosure is sealed.  Mine is not.  

--------------------
Chuck H
3D Printer Review Blog...
Posted : 13/01/2021 2:58 am
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