# How do I tell if a filament is low quality?

Low quality shows up as inconsistent diameter, bubbles, a spool that is brittle out of the bag, or a tangle. For consistency, the consensus names Polymaker, Prusament, and Bambu rather than an unlabeled spool.

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](/answers/flow).
- Bubbles in the strand, or popping at the nozzle. Stop and dry, then look again. The [drying guide](/answers/drying) 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](/brand/polymaker/polylite-pla), [Prusament PLA](/brand/prusament/pla), [Bambu PLA Basic](/brand/bambu-lab/pla-basic), and [Prusament PETG](/brand/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](/answers/pla_print) 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.

Updated 2026-10-15. Sources accessed 2026-10-15. Use case: Troubleshooting.

## Ranked filaments

| Rank | Filament | Nozzle | Bed | Price per kg |
| --- | --- | --- | --- | --- |
| 1 | Polymaker Polylite PLA | 190–230 °C (374–446 °F) | 25–60 °C (77–140 °F) | — |
| 2 | Prusament PLA | 205–225 °C (401–437 °F) | 40–60 °C (104–140 °F) | — |
| 3 | Bambu Lab PLA Basic | 190–230 °C (374–446 °F) | 35–45 °C (95–113 °F) | — |
| 4 | Prusament PETG | 240–260 °C (464–500 °F) | 70–90 °C (158–194 °F) | — |

## 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

- [PolyLite PLA technical data sheet](https://cdn.shopify.com/s/files/1/0548/7299/7945/files/PolyLite_PLA_TDS_EN_V5.4.pdf) (datasheet)
- [Bambu PLA Basic technical data sheet V3.0](https://cdn.shopify.com/s/files/1/0584/7236/6216/files/Bambu_PLA_Basic_Technical_Data_Sheet_bf3411ce-be39-4db7-9669-1b4671d2196b.pdf?v=1734060943) (datasheet)
- [Prusament PETG technical data sheet](https://www.prusa3d.com/file/3464616/prusament-petg-technical-data-sheet.pdf) (datasheet)
- [Polymaker US PolyLite PLA product page](https://us.polymaker.com/products/polylite-pla) (manufacturer)
- [Community source, r/3Dprinting 1trwxjs](https://www.reddit.com/r/3Dprinting/comments/1trwxjs/) (reddit)
- [Community source, r/ender3 13th5fo](https://www.reddit.com/r/ender3/comments/13th5fo/) (reddit)
- [Community source, r/3Dprinting 1gt9s76](https://www.reddit.com/r/3Dprinting/comments/1gt9s76/) (reddit)
- [Community source, r/FixMyPrint u2qayz](https://www.reddit.com/r/FixMyPrint/comments/u2qayz/) (reddit)
- [Community source, r/3Dprinting 1frhu4s](https://www.reddit.com/r/3Dprinting/comments/1frhu4s/) (reddit)

HTML: https://filamentfacts.com/answers/filament_quality