65 °C for 4 to 6 hours, and the data layer marks this as required rather than advisable.
PETG's heat deflection band runs 68 to 80 °C, so 65 °C sits safely below the point where the coil would soften. That headroom is why PETG can be dried at a temperature that would destroy a PLA spool.
Wet PETG announces itself
Where damp PLA degrades quietly, damp PETG is unmistakable:
- Audible crackling or hissing at the nozzle as trapped water flashes to steam
- Bubbles and pits in what should be a glossy surface
- Far more stringing than the same spool produced when it was new
- Weak layer bonds, because the steam pockets are voids
That list is the reason people spend days tuning retraction on a problem that was never a retraction problem.
It absorbs faster than you expect
PETG is genuinely hygroscopic. A spool left on an open shelf through a humid summer can be noticeably worse in weeks, not months — and it will be heavier on the scale, which quietly corrupts any estimate of how much filament is left on it.
If you keep PETG loaded in the machine between jobs, keep the machine's spool holder inside a dry box or accept that you are drying it again before anything important.
How to tell it worked
Weigh the spool before and after. A meaningfully wet reel loses measurable mass in a drying cycle; a dry one does not change. That is a more reliable test than looking at the print, because the print has too many other variables in it.
If the mass has not moved and the symptoms persist, the problem is temperature or retraction after all.
The filled grades want longer
PETG-CF is stored with a 6 to 8 hour schedule at the same 65 °C, because the chopped fibre holds water at the interface with the polymer and takes longer to give it up. Straight PET goes further again — 6 to 8 hours at 70 °C, reflecting its higher softening point.
The electricity behind a cycle is trivial — check yours by entering the dryer's wattage and hours in the print cost calculator. Every copolyester's schedule is listed on its own material page, PETG's included, and the drying guide covers equipment, sealed storage and how to tell a dried spool from a merely warm one.