FilamentFacts

Troubleshooting

How do I tell if a filament is low quality?

First in this ranking: Polymaker Polylite PLA.

Ranked filaments

RankFilamentMaterialNozzleBedPrice / kgDatasheetBuy
1Polymaker Polylite PLAPolymaker, one of the three brands named for consistency. PolyLite PLA stores a nozzle of 190–230 °C (374–446 °F), a bed of 25–60 °C (77–140 °F), and drying at 55 °C (131 °F) for 6 h. Diameter tolerance on the row is not used here as a quality score. That field is not tied to a manufacturer check.PLA
190–230 °C (374–446 °F)
25–60 °C (77–140 °F)
—Datasheet
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2Prusament PLAPrusament PLA, the second named brand. The catalog stores a nozzle of 205–225 °C (401–437 °F) and a bed of 40–60 °C (104–140 °F) from the Open Filament Database. No drying time is stored.PLA
205–225 °C (401–437 °F)
40–60 °C (104–140 °F)
——
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3Bambu Lab PLA BasicBambu, the third named brand. PLA Basic’s sheet lists a nozzle of 190–230 °C (374–446 °F), a bed of 35–45 °C (95–113 °F), and drying at 50 °C (122 °F) for 8 h. A known sheet is the point, not a secret PLA formula.PLA
190–230 °C (374–446 °F)
35–45 °C (95–113 °F)
—Datasheet
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4Prusament PETGPrusament PETG, same brand on a second material, with a datasheet. The catalog stores a nozzle of 240–260 °C (464–500 °F) and a bed of 70–90 °C (158–194 °F). The quality signs below are not PLA-only.PETG
240–260 °C (464–500 °F)
70–90 °C (158–194 °F)
—Datasheet
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Judge the spool in your hand. The consensus is not a brand ranking table. It is four defects, and a preference for Polymaker, Prusament, and Bambu when the goal is consistency.

What to look for

  • Inconsistent diameter. A filament that measures thick and thin along one meter will under- and over-extrude even with a correct flow value. Calibrating flow will not average that out. See flow calibration.
  • Bubbles in the strand, or popping at the nozzle. Stop and dry, then look again. The drying guide is the temperature list.
  • Brittleness out of the box. A new spool that snaps with a gentle bend is on the list. A spool that lived open on the printer may be moisture instead.
  • Tangles. A knot under the top layer will click, grind, and then clog. Unwind to the knot. Do not feed it.

What this catalog will not tell you

PolyLite PLA, Prusament PLA, Bambu PLA Basic, and Prusament PETG are here because those brands are the ones named. Their nozzle and bed cells are printing settings. They are not a quality grade.

The diameter tolerance stored on a row is not used as a score. The field does not say which instrument measured it.

Cheap versus bad

How do I get good PLA prints already treats a no-name spool as one cause of a bad print, after the first layer. A known brand with bubbles still fails this page. An unknown brand with an even diameter, no bubbles, and no tangle can print. The consensus preference is the named brands when you would rather not test that.

Pros and cons

Pros

  • The signs are observable on the spool: diameter, bubbles, brittleness, tangles.
  • The brands are the three the consensus names, and each has a catalog row.

Cons

  • This page cannot score a spool from the stored diameter tolerance. That number is not a lab report on these rows.
  • A known brand can still arrive wet or tangled. The signs still apply.

Printer considerations

Printer limits

What the community says

The consensus signs of bad filament are inconsistent diameter, bubbles, brittleness out of the box, and tangles. The same consensus favors established brands for consistency and names Polymaker, Prusament, and Bambu.

Sources & notes

Accessed 15 October 2026.

Answer JSON · Markdown

Related questions

Questions

Is a brittle PLA spool always low quality?

Out of a fresh bag, brittleness is one of the signs in this consensus. PLA that snapped after months in the open can also be wet. Dry it once, using the drying guide, and then decide. A spool that was brittle before it ever saw room air is the quality case.

Does a tighter catalog tolerance mean a better brand?

Not on this site. Several rows store a diameter tolerance and do not record who measured it. Consistency here means the signs above and a brand the consensus already named.