Why does filament bubble or pop while printing?

A pop that leaves a hole is the wet-spool description in the comments that are about printing. How to dry the spool, and which threads are not moisture, is already written. This page only separates those cases.

The pop

a Reddit thread in r/FixMyPrint: "Popping sounds are a clear sign of filament that has absorbed moisture. The popping sound is the water literally boiling and exploding out as vapor as it hits the extremely hot nozzle. This explosion of vapor blows the surrounding filament away creating holes or pockets where it happens. Just need t…". "A popping sound really indicates wet filament. The water evaporates in the nozzle, the steam has a bigger volume than the liquid water, and by that you get a gap in your print."

The same thread, including the comment that a pop can be an air gap, is which filaments absorb moisture. The temperatures and the dataset are drying and the filament drying dataset. Closed storage is storage. PETG stringing is the next symptom if the spool is dry and still hairy.

The post printed PLA at 200 °C (392 °F) and a 60 °C (140 °F) bed. That pair sits inside SUNLU PLA, 190–230 °C (374–446 °F) and 50–70 °C (122–158 °F), and inside PolyLite PLA, 190–230 °C (374–446 °F) and 25–60 °C (77–140 °F), with 60 °C (140 °F) at the top of the PolyLite bed. PETG HF lists drying at 65 °C (149 °F) for 8 h. SUNLU PETG lists 240–260 °C (464–500 °F), a bed of 60–70 °C (140–158 °F), and drying at 60–65 °C (140–149 °F) for 6–8 h. Do not copy the 8 h onto the SUNLU row.

The camera thread

a Reddit thread in r/prusa3d is about cheap cameras, one for each printer. "I have that first camera, it really likes to overheat, even with a heatsink on it. Other than that they're great though." That is not a filament bubble.

The PETG bubble discussion that does have comments is on the wet-filament page, from an earlier bank. PLA and PETG are the material hubs. SUNLU and Polymaker are the brand indexes.

Questions