Quick diagnosis
If a failed print, or a layer of cured resin, is left stuck to the clear film at the bottom of the vat instead of hanging from the build plate, the cause sits in the peel step, not in exposure time or plate calibration. Each layer has to release from the FEP as the plate lifts, and when that release fails, the resin bonds to the film harder than it bonds to the layer above it.
1. Slow down the lift and retract speed
A peel speed that is too fast does not give a cured layer enough time to separate cleanly from the FEP before the next lift begins, and the suction from a fast separation can pull the layer off the model instead of off the film. Most slicer profiles default to a speed tuned for the manufacturer’s own resin; with third-party resin or a heavier model, try dropping the lift speed and adding a short pause before each retract. Slower almost always works better than faster here.
2. Check the FEP tension, not just its condition
Fix Failed Resin Prints covers scratched or punctured film, but a film with no visible damage can still cause this if it has gone loose. A slack FEP flexes more during the peel, which increases how much surface area of the film stays in contact with the cured layer instead of releasing evenly. Tighten the screws around the vat frame in a crossing pattern, the way you would a bike wheel, and tap the film afterward; a properly tensioned FEP gives a taut, drum-like sound rather than a dull thud.
3. Watch for haze even without scratches
FEP film degrades with UV exposure over time, and it can turn hazy or slightly cloudy long before it develops a visible scratch. That haze roughens the surface at a microscopic level, which gives cured resin more to grip onto. If a film has run through several liters of resin and starts causing more stuck layers even though it looks intact, replacing it on a schedule rather than waiting for visible damage is the more reliable fix. FEP film replacement covers the swap procedure itself.
4. Give resin time to flow back between layers
A short lift distance or a rest time set to zero does not give displaced resin enough time to flow back under the film before the next exposure starts. That leaves the next layer without enough material right where it needs to bond, and a thin bond like that is more likely to let go and stay behind on the film. Increasing lift distance slightly, or adding a short rest pause, gives the vat time to level out before the next layer prints.
Resin stuck to FEP checklist
- Lift and retract speed slowed, especially for third-party resin or heavier models.
- FEP tension checked with a tap test, not just a visual scratch check.
- Film replaced on a usage schedule if it has gone hazy, even without visible damage.
- Lift distance or rest time increased so resin can flow back before the next layer.
- Plate calibration and exposure time ruled out separately if this checklist does not fix it.
If the print never touches the plate at all, rather than releasing back onto the film, start with Fix Resin Prints Not Sticking to the Build Plate instead. For scratched or punctured film rather than a tension or haze problem, see Fix Failed Resin Prints.