The first time this happened, I thought maybe I had accidentally left a piece of tape on the printing bed. Why? Because the black sticky area was tape-shaped, I was able to peel off a thin layer both on the print bed (after object removed) and also on the object itself. The sticky area remained, so I was careful not to print on it. I could not remove it, was thinking of trying fingernail remover, but did not get any yet.
Next time printing went well, not printing on sticky area.
However, the next time, look what happened. Note: there was nothing on the print bed before I started, except for the first sticky area. The object stuck so well to the bed that taking it off damaged the bed surface, and left a few more of these black sticky areas. Again, I was able to pull off the thin layers from these on the object (but not from the bed this time), and the bed is a mess - surface bubbles and even a tear.
What is going on? I am using the standard settings for PETG, which is 80° C for the bed, 250°C for the extruder. I am using Overture black PETG filament.
Note: 3 shiny black sticky areas: bottom one is from the first print. Top two are from final print,
It looks like is a PEI bed? Generally pei with PetG recommends glue stick as a resist. PetG sticks too well to pei. It is a possibility that it is the pei sticker that is lifting.
Yes as @kitedemon stated petg requires gluestick in order to print it. The gluestick isn’t for extra adhesion, as you have found out PETG has pretty good adhesion. The gluestick acts as a sacrificial layer so it will take a chunk from the gluestick instead of a chunk from the bed.
PETG will even take chunks out of glass beds if you don’t put something down, ask me how I know…
Matthew, how do you know…?
Well, that is interesting… I have printed with PETG for a long time, never put anything down. Hmmm. Anyway, With 3DPrinting tech support, I got a full replacement bed from Creality. I suspect a bad run or something. However, now I am using a textured surface, and that has been interesting. I have to set bet to 90°C to ensure 1st and 2nd layer adhesion. But now, I am thinking it is all about letting it cool before I grab it… That seems to work. I was too impatient to wait for cooling so I pulled it off too soon. So maybe 80°C may work just fine…
I refused to buy a printer with a glass plate with PEI surface. Hard to bend.
Don’t ask about my build plate graveyard, its still a bit of a soft spot. Congrats on having no issues, this is the luck we all wish for! Whatever you are doing you are doing right.
