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Is there a way to test if filament is PETG?  

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jweaver
(@jweaver)
Honorable Member
Is there a way to test if filament is PETG?

I have bought my first ever PETG filament and it dawned on me that I have no way of knowing what its actually made off.. It was dirt cheap and just because it says PETG on the label doesn't mean it is..

I have just loaded it in my Printrbot and set the temperature to 190 and started to push out the old PLA.. I assumed that when the PLA was through it would stop, as PETG should have a higher melting point. But it carried on extruding the PETG even at 190... I am now heating up the bed and Nozzle to PETG temperatures and am going to do some test prints....

But is there any way to confirm that its not PLA badged as PETG?

Posted : 25/01/2018 7:33 pm
jweaver
(@jweaver)
Honorable Member
Topic starter answered:
Re: Is there a way to test if filament is PETG?

I think its OK.. I ran it under some boiling water with some PLA.

The PLA went soft and floppy, and I could stretch it.. The PETG went a little flexible, but certainly didn't melt.

I think I am just being paranoid, but must admit, I didn't think it would liquefy at such low temps.

Posted : 25/01/2018 7:48 pm
Paul Meyer
(@paul-meyer)
Honorable Member
Re: Is there a way to test if filament is PETG?

I suspect it is likely PETG. Not at all definitive, but in my experience:

  • PETG can be be transparent/translucent, PLA/ABS never are for me. I've got some solid black PETG, and Prusa has solid Orange, so doesn't always help

  • PETG printed thin is pretty flexible compared to PLA/ABS. Print a 0.5mm thick business card sized piece and see how it flexs compared to PLA

  • it can sometimes be quite stringy (think taffy). This can be a problem, but for me it is indicitive of PETG.
  • Posted : 25/01/2018 9:11 pm
    RotaryDane
    (@rotarydane)
    Eminent Member
    Re: Is there a way to test if filament is PETG?

    You can also try holding a small piece of filament over a naked flame and smell the smoke it gives off.
    As PETG decomposes it gives off some of the added Glycol as vapor, which has a destinct sweet smell to it.
    I remember from having to melt brass threaded inserts into PETG parts, the smell would linger for quite a bit.

    Posted : 25/01/2018 11:30 pm
    Kwaad2
    (@kwaad2)
    Honorable Member
    Re: Is there a way to test if filament is PETG?


    You can also try holding a small piece of filament over a naked flame and smell the smoke it gives off.
    As PETG decomposes it gives off some of the added Glycol as vapor, which has a destinct sweet smell to it.
    I remember from having to melt brass threaded inserts into PETG parts, the smell would linger for quite a bit.

    So that's what getting cancer smells like!
    (On a serious level, AvE smells all his plastics to identify them, along with meting temps... It works quite well)

    Hi, I'm Sean. I used to work on CNC machines.
    I try to not make mistakes, but the decision is YOURS.
    Please feel free to donate to my filament/maintance fund.

    Posted : 26/01/2018 12:23 am
    HackMonkey
    (@hackmonkey-2)
    Trusted Member
    Re: Is there a way to test if filament is PETG?

    I was just reading a few days ago that Ethyl Acetate (fingernail polish remover) can smooth PETG. Haven't tried it yet though.

    https://www.matterhackers.com/articles/how-to-post-processing-petg-3d-filament

    Posted : 26/01/2018 1:32 pm
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