I print almost exclusively now in PETG. I just love the material. It's super strong, non stinky toxic, and feels like a "real" material. But I have one huge problem, the glop.
Step 1: Fix the PETG Glop
Here is the glop in all its glory. This is right after a great print, one that is pitch perfect, and there is a ton of gooey ickiness all over the E3D hotend.
This isn't something that I've experienced with PLA, and since when I print with ABS, I do it at work in an enclosed industrial system that I don't have at home (I use a Prusa i3 MK3,) I don't know if this an ABS issue. But it is definitely a PETG one.
PETG is amazingly surface-philic. It just loves to find a surface and bind to it. People say things about the filament material like it sticks hard to everything, and they're right. Unfortunately for current consumer machines, that means it doesn't necessarily choose to stick to where the manufacturing is happening, especially when it decides to stick to the E3D hotend block. Want to see this for yourself? Try this experiment: extrude a little bit of the filament and gently blow on it while extruding, simulating an air current in the room. Suddenly you have several loops of filament, including all over the E3D hotend and crawling up and over everywhere. No fun unless you like random glops of PETG that drop whenever they like into your print.
Step 2: So You Solve It With a Sock, Right? WRONG.
So PETG is crawling all over the E3D V6 hotend, and they make a silicone sock for the hotend, so use it to protect your hotend from this creepy PETG badness! Genius!
Ugh, not so easy. I have a Prusa machine that I constructed from a kit (and oh my goodness, that was one incredible joy--the build was even more fun than the use of the printer, the graphic design of the instructions and the industrial design of the printer was so remarkable,) and I wondered why the * they didn't include that sock in the kit. Now I know.
The sock does nothing to prevent PETG from crawling up and all over the E3D V6 hotend. It just hides it. I tried the sock with the little hole for a E3D V6 nozzle tip and the one with the bigger hole for the nozzle screwed into the block and both were excellent at hiding the PETG from crawling up and all over the block while doing nothing to prevent it from doing so.
So I am not a fan of the sock.
Step 3: You Solve the Problem by Cleaning the Glop When It Happens...
I have an Olsson Ruby nozzle, otherwise I'd just scrub the nozzle and block down with steel wool. I can't do that with the Olsson Ruby, as it would chip the ruby. So after preheating to PETG temperature, I carefully scrub the block around the nozzle with the stainless steel HDX mini brush that I get in a 3 pack from Home Depot for about $4 USD and then I use the nylon mini brush to gently clean the glop off the nozzle itself.
Step 4: ...and Try to Prevent It.
I also add G-code (here shown in Slic3r) to try to prevent the glop by retracting 2 cm at the end of each print:
G1 E-20.0 F1200 ; retract filament
And this means a little longer first run to get the filament flowing at the beginning of each print:
G1 X144.0 E18.0 F800.0 ; intro line
G1 X240.0 E24.0 F800.0 ; intro line
(Which of course is specific to the size of the bed, a smaller bed would warrant less retraction and require a shorter intro line.)
And, most importantly, I move the head up at the end of each print so that I can see the glop and clean it when it's forming:
G1 Z197 F900 ; Move print head up
Step 5: And That's How I Deal With the E3D V6 PETG Glop...
By fixing it, not hiding it!