A filament dryer is a heated, low-humidity chamber. It is one of the few accessories that measurably changes print quality, but the useful specification list is short.
Temperature range decides which materials you can dry
Different polymers need different drying temperatures, and the range is wide. As a working guide: PLA and TPU sit at the low end, PETG in the middle, and ABS, ASA, PC and PA at the high end. A dryer that only reaches around 50 °C will handle PLA and TPU comfortably but will take much longer on PETG and cannot properly dry nylon. Check the maximum temperature and how precisely it holds it, not the number printed on the box lid.
Capacity and spool width
Single-spool units are fine for occasional work. If you run several printers, a two-spool chamber saves more time than a faster heater. Confirm the chamber accepts wide 1 kg spools, because some compact dryers only fit narrow ones.
Seal and airflow
A dryer without a reasonable seal simply pulls moisture back in from the room. A gasket, a closable lid and a desiccant compartment are worth more than an extra display feature. Continuous drying during long prints is a useful bonus for hygroscopic materials.
What a dryer cannot do
Drying cannot restore filament that has been overheated, and it does not fix a spool that was wound badly. It also does not replace storage: filament dried and then left in humid air reabsorbs moisture within days. Dry, then store sealed.
The pay-off is easy to see. Dry PETG strings less, nylon prints more consistently, and TPU stops popping at the nozzle. If you are unsure whether your material needs drying, start with one spool and compare surface finish before and after.
See FilamentLab material grades or ask our team for drying profiles for a specific polymer.