What's so special about cleaning filament?
You may discover that "cleaning filament" is also described as nylon filament. Nylon requires higher temperatures than most commonly used filaments. As you raise the hot end to the required temperature to melt the nylon (typically 250°C, all of the other debris has either carbonized or melted.

The hot end is allowed to cool (30-50°C) at which point the nylon filament is pulled out in the reverse direction. Some 'net references suggest a hard pull, but I disagree with violent mechanical forces being applied to delicate mechanical devices. Perhaps that's why my cleaning process takes two to four attempts. Some net references also suggest to start the nozzle heating after reaching the cooling point and to begin applying force upward during the re-heating.

My Sigma 16 uses the above method and also suggests a "strong pull" which is a translation from "sharp yank," in my opinion.

This will collect the debris from the nozzle and heat break and may completely clean the filament path.

I use "natural" clear nylon for cleaning and perform the sequence two to three times, until the heated portion of the nylon no longer has contamination visible.

Even nylon filament that is not dry enough for printing works for cleaning. The moisture bubbles turn the filament into flimsy punctured nylon thread, but it causes no problem with the cleaning process.

FilamentOne website references most of what I've posted.



The above image resembles my experience, although the severely "dirty" image is much more excessive than my cleanings. The worst is to have PVA support material that has been "cooked" at ABS temperatures or higher for long periods. An almost guaranteed nozzle clog is the result of those conditions.