SLA / MSLA Resin Printing Troubleshooting: 13 Top Failures & Fixes
Complete guide to resin 3D printing failures: from prints sticking to FEP to cupping blowout. Concrete exposure, lift speed, and film-replacement settings for every current printer — Anycubic, Elegoo, Phrozen, Creality, Formlabs, Prusa.
SLA / MSLA / DLP printing delivers detail FDM will never match — but the price tag is a vat of liquid resin under the build plate and a dozen finicky parameters. One wrong bottom exposure, an aged FEP film, or a forgotten drain hole, and the entire job becomes a sticky mess at the bottom of the tank.
This guide covers the 13 most common SLA/MSLA failures: from the classic "print stuck to the film" to subtle defects like elephant foot and cupping blowout. Only proven fixes with concrete numbers for exposure, lift speeds, and slicer parameters. Applies to all current models: Anycubic Photon Mono M5s/M7 Pro, Elegoo Saturn 4 Ultra, Phrozen Sonic Mighty Revo, Creality HALOT-Mage S, Prusa SL1S, and Formlabs Form 3/4.
How resin printing works and where it breaks
An MSLA printer doesn't melt plastic — it projects a UV mask from an LCD through a transparent FEP film onto the bottom of a resin vat. Each layer is exposed for 1-3 seconds, then the build plate lifts to peel the print off the film, and lowers again by one layer thickness.
All failures revolve around three physical processes: polymerisation (UV time and power), peel force (separating the layer from FEP on lift), and adhesion (the print sticking to the build plate). Break any one of them — and the print fails. That's why most "magic recipes" boil down to balancing exposure, lift settings, and consumable condition.
• Plate lifts empty → under-exposure, dirty film, low resin level
• Print on FEP, not on plate → bottom-layer under-exposure, smooth plate, worn FEP
• "Elephant foot" at base → bottom over-exposure + no rest time
• Hollow models with split walls → no drain holes, suction cup
• Horizontal banding → high lift speed, worn FEP, temperature swings
Main causes of failure and their frequency
Based on community-forum statistics (Reddit r/resinprinting, Anycubic/Elegoo forums, Phrozen Help Center), failures break down roughly like this:
| Cause | Failure share | Main symptom |
|---|---|---|
| Bottom-layer under-exposure | ~25% | Print stays on FEP, plate is clean |
| Cold resin (<22 °C) | ~18% | Seasonal — worse in winter, peel force higher |
| Worn FEP film | ~15% | Cloudy print zone, banding, corner failures |
| Weak supports | ~12% | Mid-print detachment, model intact, supports fell off |
| Suction cup on hollow models | ~10% | Horizontal blowout through the wall |
| Dirty build plate | ~8% | Adhesion like wet soap |
| Mis-leveled plate | ~5% | Corners stick differently, print skewed |
| Other (LCD, power, firmware) | ~7% | Random one-off errors |
Fix #1: Build plate calibration and flatness check
With a poorly leveled or warped plate it's pointless to tune exposure — the print won't stick at any duration. This is the first thing to check if a model fails on the FEP in the same corner every time.
- Remove the vat, wipe the plate bottom with a lint-free cloth and 91%+ IPA
- Place a flat sheet of paper (80 g/m²) between the LCD and the plate
- Loosen the plate lock screw, lower it to the paper
- Pull the paper firmly — there should be even resistance on all 4 corners
- If paper slides freely in one corner and grabs in another — the plate is warped, replace it
- Tighten the central screw, run Z=0 home, save the position
Fix #2: Warm resin to 25-30 °C
Cold resin thickens, peel force triples, and exposure works worse due to viscosity. This causes "seasonal" issues where the printer suddenly stops working in winter for no obvious reason.
- Ideal working temperature is 25-30 °C for most resins
- At 18-20 °C (typical winter apartment) almost any resin runs at 50-70% of its potential
- Modern printers (Anycubic M7 Pro, Elegoo Saturn 4 Ultra, Phrozen Sonic Mighty Revo) have built-in heaters — turn them on 30 minutes before print start
- Without built-in heat: a 25 W aquarium heater in the vat, a heating mat under the printer, or warming the room for 1-2 hours
- Soak the resin bottle in warm water for 15 minutes before pouring, then mix thoroughly (especially for coloured resins — pigment settles)
- Never use a hairdryer or direct heat — local overheating above 40 °C triggers premature polymerisation
Fix #3: Calibrate exposure with the Cones of Calibration
"Bottle-recommended" exposure is a starting point, not a final value. Real optimal time depends on your LCD's UV power, screen condition, resin temperature, and even pigment density. The industry standard for calibration is the Cones of Calibration V3 by TableFlip Foundry.
- Download Cones of Calibration V3 (free on TableFlip Foundry's site or MakerWorld)
- Slice with your standard bottom exposure and lift-speed settings
- Set normal exposure per the resin bottle (typically 1.8-3.0 sec for 8K LCD)
- Print, wash in IPA for 1-2 min, let dry, do NOT post-cure (it ruins the calibration)
- Side A (Success): all cones must print. If even one is missing — exposure is too low, +0.2-0.4 sec
- Side B (Pillars): pillars must be distinct, not fused. If fused — over-exposed, -0.2-0.4 sec
- Ideal result: all cones on A + 8-10 distinct pillars on B
- Record the value for each resin — it takes minutes, saves hours of failures
Starting exposure values by resin type
| Resin type | Normal exposure (8K LCD) | Bottom exposure | Bottom layers |
|---|---|---|---|
| Standard grey/black | 2.0-2.5 sec | 30-40 sec | 5-6 |
| Clear / white | 3.0-3.5 sec | 40-50 sec | 6-7 |
| Dark (blue, burgundy) | 2.5-3.0 sec | 35-45 sec | 5-6 |
| High-speed (Anycubic High Speed, Phrozen Aqua-Speed) | 1.0-1.5 sec | 20-25 sec | 4-5 |
| Engineering / tough (ABS-like) | 2.5-3.5 sec | 40-60 sec | 6-8 |
| Flexible (Flex / Tough) | 3.0-4.0 sec | 45-60 sec | 6-8 |
| Dental (Dental Model) | 2.0-2.8 sec | 40-50 sec | 6-7 |
Fix #4: Elephant foot — first-layer blooming
Elephant foot is the model's bottom flaring outward as the first 3-5 layers "bloom". Most guides advise lowering bottom exposure — that's wrong: you'll get weak adhesion and a torn-off print. The real cause is squeezed resin under the plate that polymerises around the edges before it can flow away.
The correct fix is adding rest time before exposure (a pause after lowering, before exposure starts). The resin has time to flow out from under the plate, and lateral blooming disappears.
- Open the printer profile in ChiTuBox / Lychee → Bottom layer settings
- Find Rest time before exposure (or Wait time before cure in Lychee)
- Set 20-30 seconds for bottom layers (default is 0)
- Set 1-2 seconds for normal layers (helps with layer lines)
- Keep bottom exposure unchanged (30-40 sec) — DO NOT reduce it
- Verify on a 20×20×20 mm test cube — if blooming is gone, apply to real models
- For large models (>50 cm² of plate contact) add a 0.5 mm chamfer along the bottom edge in CAD
Fix #5: Peel force and lift settings
Every time the plate lifts, the print peels off the FEP — that's peel force. Too fast → the part tears or detaches from the plate. Too slow → printing takes 2-3× longer.
| Model type | Lift speed (phase 1) | Lift speed (phase 2) | Lift distance | Retract speed | Rest after retract |
|---|---|---|---|---|---|
| Standard (Z-lift, no tilt) | 60 mm/min | 180 mm/min | 6-7 mm | 150 mm/min | 1-2 sec |
| Large (>50 cm² contact) | 50 mm/min | 150 mm/min | 8-10 mm | 120 mm/min | 2-3 sec |
| Thin / detailed | 40 mm/min | 120 mm/min | 6-7 mm | 100 mm/min | 1-2 sec |
| Flexible resin | 30 mm/min | 100 mm/min | 8-10 mm | 80 mm/min | 3 sec |
| Tilt mechanism (M7 Pro, Saturn 4 Ultra) | tilt | tilt | — | — | 0.5 sec |
The tilt mechanism (vat tilting instead of plate lifting) is the past 2 years' breakthrough: peel force drops 2-3×, prints speed up without quality loss. If you're picking a new printer — go for one with tilt.
Fix #6: Hollow models and drain holes against the vacuum effect
Any hollow model without drain holes becomes a giant suction cup. Each plate lift creates a vacuum inside the cavity, and peel force grows 5-10×. Result — cupping blowout: the model splits horizontally through the wall.
- Any hollow model MUST have at least 2 drain holes
- Hole diameter: 2-4 mm (2 mm for miniatures, 4 mm for large parts)
- Placement: one near the plate (vents air on lowering), one at the top (drains residual resin on lift)
- Hollow wall thickness: 1.5-2 mm for smooth surface, minimum 1.2 mm
- Don't trust Lychee Magic mode on complex multi-cavity models — add drain manually
- For miniatures (Warhammer etc.) Lychee Auto Hollow + Auto Drain works fine — 2-3 holes on the bottom
- If printing a bust — drain below the chin + on the top of the head
Fix #7: FEP film — tension, replacement, and choosing the right type
FEP is the main MSLA consumable. The film wears every print, and skipping replacement = chronic failures plus the risk of damaging the LCD ($80-150 in repairs).
Film type comparison
| Type | Lifespan | Peel force | Price | When to use |
|---|---|---|---|---|
| FEP (standard) | ~10,000 layers / 200-300 hrs | High | $3-5 | Standard resins, beginners |
| nFEP (PFA) | ~30,000 layers | Medium | $8-12 | Thin models, miniatures, faster prints |
| ACF (Advanced Composite) | ~30,000 layers | Minimal (3× lower than FEP) | $15-20 | High-speed resins, 8K-14K LCD, large models |
Signs FEP needs replacement:
- Cloudy area in the centre of the print zone (where prints land most often)
- Visible scratches deeper than 0.1 mm
- Whitish "ghost" prints from previous models — fatal sign
- Finger-tap test sounds dull instead of crisp (lost tension)
- Pinhole test: place FEP on a dry paper towel, pour IPA on top — wet spots = leaks
Fix #8: Supports — settings in ChiTuBox / Lychee
Supports are the only way to hold up overhangs and angled surfaces in resin. Weak supports = mid-print detachment. Too aggressive = scars on the surface after removal.
Recommended support parameters
| Parameter | Light supports | Medium supports | Heavy supports |
|---|---|---|---|
| Tip diameter (model contact) | 0.20-0.25 mm | 0.40-0.50 mm | 0.60-0.80 mm |
| Upper diameter (body) | 0.40 mm | 0.55 mm | 0.70 mm |
| Lower diameter (base) | 0.50 mm | 0.70 mm | 1.00 mm |
| Contact depth | 0.15 mm | 0.20 mm | 0.30 mm |
| Density (auto-supports) | 60% | 75% | 90% |
| Where to use | Miniatures, thin parts | Standard models | Large/heavy parts |
- Never trust Auto-supports alone — review the model from all angles after generation
- Angles >45° to the plate MUST be on medium-supports, overhangs — heavy
- Model angle 30-45° to the plate is optimal: less peel force + better support orientation
- For miniatures (Warhammer) enable Anti-aliasing in the slicer — corners come out cleaner without aggressive tips
- Tip diameter <0.20 mm almost always breaks — bump to 0.25-0.30 even on light
- Under heavy zones (flat surfaces 5×5 cm or larger) place medium-supports manually with 3-4 mm spacing
- Heavy supports under faces and key details = scars. Flip the model upside down if possible
Fix #9: Horizontal layer lines on prints
Thin lines on side walls are another common resin defect. There are 5-7 possible causes, and you need to diagnose them by the line's character.
| Line character | Cause | Solution |
|---|---|---|
| Regular through full height | Z-axis wobble, loose dovetail screw | Tighten the rail, check for play |
| Lines at support bases | Lift speed too high | Drop to 60 mm/min (phase 1) |
| Sharp line at one height | Air bubble in resin during exposure | Stir resin with a spatula before printing, pour gently |
| Thin lines through full height | Worn FEP film | Replace FEP |
| Pattern changes mid-print | Temperature swing (day/night) | Enclosed box or resin heater |
| Thin lines every 50-100 layers | Periodic printer pauses (Anycubic M-series) | Disable Pause periodic in printer settings |
| Only in one zone | Dirt/scratch on LCD | Remove protective film, wipe with IPA + microfibre |
Fix #10: When the print sticks to FEP instead of the plate
This is the top-1 issue for every beginner. Symptom: the plate is empty after print, and a pile of flat resin chunks sits at the vat bottom. There can be several causes — work through them in order.
- Step 1: Clean the plate with IPA + lint-free cloth. Verify with the paper test after
- Step 2: Bump bottom exposure +25% (e.g. 30 → 38 sec)
- Step 3: Increase bottom layers from 5 to 7-8
- Step 4: Drop phase-1 lift speed to 40-50 mm/min
- Step 5: Add a raft — boosts contact area
- Step 6: Check FEP tension — finger tap should sound crisp
- Step 7: If nothing else helps — lightly scuff the plate with P200-P400
- Step 8: Plate is warped (paper slides freely in one corner) — replace it
Per-printer and platform notes
Most issues are universal across MSLA — physics is the same. But specific brands and models have nuances that change recommended settings.
Anycubic Photon Mono M5s / M7 Pro / Photon D2
- M7 Pro and M5s have a built-in resin heater — turn it on 30 min before print, hold 28 °C
- Anycubic's ACF film fits M5s/M7 — 2-3× speed boost vs FEP
- Mono M3/M5 issue — factory-smooth plate, MUST scuff with P400 before first print
- Photon D2 (DLP) — forget FEP issues, but the projector wears out at 2,000-3,000 hrs
- Photon Workshop defaults rest-time to 0 — set 1-2 sec on normal, 20+ sec on bottom
Elegoo Saturn 4 Ultra / Mars 5 Ultra
- Tilt mechanism (Saturn 4 Ultra 16K) — only nuance: lift settings replaced by tilt angle and tilt speed
- Resin heater present on 4 Ultra and 5 Ultra — always enable
- 3rd-party ACF films are compatible (5× cheaper than original Elegoo)
- Mars 5 Ultra — firmware v1.0.5 had Z-calibration bugs, must update to 1.0.7+
- Download the Saturn 4 Ultra Chitubox profile from Elegoo's site, don't edit the old Saturn 3 profile
Phrozen Sonic Mighty Revo / Mini 8K S
- Phrozen has the best factory FEP tension, but branded films cost more than 3rd-party
- Mini 8K S — compact, but the 8K LCD demands ACF for fast resins, otherwise peel force kills FEP in a month
- Sonic Mighty Revo — large Z-travel (235 mm) → use 2-phase lift with a long first stage
- ChiTuBox Phrozen profiles are current; in Lychee — refresh every 2-3 months
- Phrozen Aqua-Speed resins need 0.8-1.2 sec exposure — defaults over-cure
Creality HALOT-Mage S / HALOT-Mage 8K
- Creality has its own slicer HALOT Box, but ChiTuBox/Lychee also support the printer
- Early HALOT issue — unstable LCD power: over-exposure at start, under-exposure by the end. Solution — power conditioner
- Factory auto-leveling is often off — manual calibration after unboxing is mandatory
- FEP on HALOT-Mage S is held by 16 screws — tensioning needs patience and 1/4-turn crosswise pattern
Formlabs Form 4 / Form 3+ (professional segment)
- Form 4 (LFD — Low Force Display) uses a silicone layer instead of FEP — no film changes
- Exposure calibration is automatic — don't tweak it, OEM resins work out of the box
- PreForm slicer doesn't support 3rd-party resins — license restriction, not technical
- Form 3+ requires regular cleaning of the optical window (clouds from resin in 100-200 hrs)
- Cupping blowout impossible on Form 4 — built-in Cup Detection in PreForm
Prusa SL1S Speed
- Prusa SL1S — open PrusaSlicer firmware, excellent display diagnostics
- FEP replacement is a complex procedure with a tensioning jig — don't attempt without instructions
- Prusament Resin ships with preset profiles in PrusaSlicer — no calibration needed
- Third-party resins — always run Cones of Calibration before real prints
- The CW1S cure station from Prusa uses IPA vapour + filter — actually safer than open-bath washing
Post-processing: safe washing and curing
Half of all resin problems come from post-processing, not printing. An over-cured part is yellow and brittle, an under-cured one is sticky and toxic. A detailed wash & cure guide lives in our 3D Print Post-Processing article — here are the resin-specific essentials.
- Wash: 91%+ IPA or Mean Green / TPM (specialised solvents)
- Two-bath setup: 1) dirty bath — 1-2 min, active agitation; 2) clean bath — 30 sec finish
- Wash time depends on detail: miniatures 2-3 min, large parts 5 min (longer = washes detail out of crevices)
- After washing — dry with compressed air or let drip 5-10 min until IPA fully evaporates
- Cure ONLY after full drying — wet parts cure unevenly and warp
- Cure time = 2-5 min for most models under a 405 nm lamp. Over-cure >10 min = yellow tint and brittleness
- For dental and engineering resins follow the manufacturer instructions — exact time and temperature matter
Disposal: liquid resin is hazardous waste. Cure under UV until fully solid, then dispose as regular plastic. Dirty IPA — store in a sealed container, take to hazmat collection or settle in sunlight for 2-3 days (cured residue settles, clean IPA decants for reuse).
Prevention: SLA printer maintenance checklist
Most failures are preventable with regular maintenance. General principles live in our 3D Printer Maintenance Guide; below — resin-specific items.
| Frequency | Action |
|---|---|
| Before each print | Stir resin with a spatula + check level (at least 1/3 vat) |
| Before each print | Check FEP (flashlight backlight) + wipe LCD |
| After each print | Clean plate with IPA, squeegee resin off FEP with a rubber spatula |
| Every 5-7 prints | Filter resin through a 100 µm mesh when draining |
| Every 50 hours | Verify FEP tension (drum tap test) |
| Every 100-200 hours | Replace FEP (standard); 300+ hrs for nFEP/ACF |
| Every 200 hours | Tighten the dovetail screw on the Z column |
| Every 500 hours | Check LCD protective film integrity, replace if scratched |
| Once a year | Full vat cleaning with Mean Green + replace silicone seals |
Quick diagnosis: what to do right now
If your print just failed and you don't know where to start — find your symptom in the table:
| Symptom | Likely cause | First action |
|---|---|---|
| Plate lifts empty | Bottom exposure too low OR dirty FEP | +25% bottom exposure, clean FEP |
| All parts on FEP, none on plate | Plate doesn't grip (smooth, dirty) | Sand with P400, wipe with IPA |
| Model detached mid-print | Weak supports or suction cup | Thicken tips to 0.4 mm, add drain holes |
| First 3-5 layers blooming out | Elephant foot — needs rest time | Rest time 25 sec on bottom layers |
| Thin details washed out | Normal exposure too high | -15% normal exposure, run Cones |
| Coarse horizontal banding | Lift speed too high | Drop to 60 mm/min phase 1 |
| Hollow model torn apart | Cupping blowout — no drain | Add 2 drain holes Ø3 mm (bottom + top) |
| Print stalls to start, then errors | Cold resin, temperature swing | Warm resin to 28 °C, update firmware |
| LCD shows discoloured patches | Dead pixels or damaged LCD | Run UVTools Pixel Test, replace LCD |
| Smell intensifies, headache | Resin leak or poor ventilation | STOP, ventilate, check FEP, wear respirator |
Sources and helpful resources
- TableFlip Foundry — Cones of Calibration V3 — exposure calibration standard
- Honza Mrázek — Bed Adhesion & Elephant Foot Guide — deep mechanism explanation
- AmeraLabs — Resin Troubleshooting Guide — resin maker shares insight
- Anycubic Print Guides — official guides with photos
- Phrozen Help Center — film, exposure, maintenance docs
- Lychee Slicer Documentation — detailed manuals on hollow, drain, supports
- Formlabs Support — pro-grade view on SLA issues
Related Printer Hub articles
- 3D Print Post-Processing: Sanding, Painting, Smoothing — general principles plus SLA specifics
- 3D Printing Safety: Fumes, Ventilation, Health — critical for resin work
- 3D Printer Maintenance: Cleaning, Lubrication, Prevention — basics of routine care
- First Layer Not Sticking: FDM Guide — parallel article for FDM
- 3D Print Warping & Lifting — deformation, applies to resin too
The main MSLA principle: be systematic, not random. Each setting tweak deserves its own test print (Cones of Calibration or a 20-mm cube), a recorded result, and a saved good combination. In 2-3 weeks you'll have a personal database of settings per resin, and failures become rare. Happy printing!