Blooming and over-exposure: soft details and rough surfaces
These two look related but have different causes. Over-exposure makes features bloated and soft: gaps close up and text fills in. Blooming makes surfaces rough, frosted or 'cauliflower'-like, often stopping at a certain height, because the resin hadn't settled when the layer was cured.
Most likely causes (in order)
- Normal exposure too high: Excess light bleeds into neighboring areas, softening edges and fusing small details.
- Resin not settled before curing: Thick or cold resin, or no rest time, means the layer cures while resin is still moving.
- Suction in hollow parts: A cavity without a drain hole near the plate can push semi-cured resin outward.
- Heavy blur/anti-aliasing: Strong blur settings can smear fine detail on minis.
Settings to change
| Setting | Change | Why |
|---|---|---|
| Normal exposure | Reduce in small steps; use a calibration print (e.g. exposure matrix) | Over-cure bleeds light into adjacent areas (CHITUBOX). |
| Anti-aliasing / blur | Moderate AA; avoid heavy blur on minis | Preserves edge definition. |
| Wait before cure (rest after retract) | Add/increase rest time before each exposure (a few seconds; longer for thick resin) | Lets resin flow and the plate settle before curing. |
| Drain holes / orientation | Add drain holes at the lowest point near the plate; tilt to avoid cups | Removes suction that squeezes semi-cured resin outward (Lychee: Volcanoes). |
| Resin temperature | Warm resin to ~25–30 °C to lower viscosity | Thick resin settles slowly. |
Exact values depend on your printer and resin. Start from the resin maker's recommended settings and change one thing at a time.
Quick checklist
- Print an exposure calibration test and reduce exposure if over
- Keep anti-aliasing moderate and avoid heavy blur on minis
- Add a rest time before each exposure
- Warm resin to roughly 25–30 °C so it flows
- Add drain holes near the plate on hollow parts
FAQ
How do I know if my resin print is over-exposed?
Small gaps close up, holes shrink, text fills in, and details look puffy. A calibration print makes it obvious.
What is blooming in resin printing?
A rough, over-grown surface where partly cured resin stuck to the walls, usually because the resin hadn't settled before the layer cured or because of suction in a hollow part.
Not sure which one you've got?
Upload 1–4 photos of the failed print and PrintCleric ranks the likely causes and tells you exactly which settings to change, with sources.
Sources
- CHITUBOX Academy: All You Need to Know about Failed Printing
- Ameralabs: Resin 3D Printing Troubleshooting Guide
- Lychee Docs: Volcanoes
Related fixes
- Layer separation / delamination in resin prints
- Failed supports: model stuck to the FEP, only supports printed
- Nothing on the build plate (print stuck to the FEP)
- Suction cups and blowouts (volcanoes) in hollow resin prints
- Elephant's foot (flared bottom layers)
- Cracking resin prints (hollow parts and post-curing)
Wear nitrile gloves and eye protection when handling uncured resin, and work in a ventilated space.