Why the Bottom of a Resin Print Feels Different
Flip any freshly printed resin part over and you will notice the bottom surface looks sturdier than the walls. The flat base is built with longer exposure times than the rest of the model. Understanding those bottom layers — what resin slicers call the base layers, transition and burn-in — is the quickest way to fix parts that stick too hard, lean, or come out from dimensional spec.
This guide explains each hidden setting in plain terms and gives practical starting values that work well with ANTINSKY Standard Resin and Standard Lite Resin.
What Each Setting Actually Controls
| Setting | What It Does | Getting It Wrong |
|---|---|---|
| Bottom / Base layers | Number of long-exposure layers at the plate | Too few → the part peels off mid-print |
| Bottom exposure (burn-in) | Long exposure time on those layers | Too long → over-exposed, hard-to-remove base; stuck prints |
| Transition layers | Gradual steps from long exposure back to normal | Too abrupt → a visible ridge or weak seam |
| Bottom lift/retract speed | How fast the plate peels each bottom layer | Too slow → longer prints; too fast → suction failures |
| Bottom exposure count | Whole number of burn-in layers | Odd values can create an uneven first contact |
Burn-in Time: The Firm Handshake
The bottom exposure, or burn-in time, must pull the first few layers firmly onto the build plate without over-cooking them. As a rule of thumb, bottom exposure is roughly 8–12 seconds for a 50 µm layer using standard LCD resin, while normal layers run 2–4 seconds.
A Practical Starting Range
- Start with 4–6 bottom layers for most figures
- Set bottom exposure to 8–12 s for standard resin
- Raise it if the base separates; lower it if the part glues to the plate
Running Standard Lite Resin, which cures a touch faster, you can often drop the bottom exposure toward the low end of the range.
Transition Height: The Graceful Merge
Going straight from an 10-second burn-in to a 3-second normal layer leaves a visible light band around the base. Transition layers spread that change over several layers so the part eases back to normal exposure. If you notice a faint swirl or bulge near the bottom, your transition height is too short.
- Transition height is measured in layer count or millimeters
- More transition = smoother but slightly softer base wall
- For function-driven parts, keep it modest
Balancing Adhesion Against Easy Removal
The eternal trade-off: firm enough to not fail, gentle enough to remove. A good middle ground is a raised, sloped base or a small raft. On the plate side, a crisp PEI-caliber surface helps, but in resin the biggest lever is bottom exposure.
Rule of thumb: if you need a scraper and force, lower bottom exposure or fewer bottom layers. If prints come loose, raise them. Small steps, one variable at a time.
Wash, Cure and Inspect the Base
After printing, parts from Standard Lite Resin wash quickly and cure to a consistent strength across the base. A well-tuned bottom ensures the flat underside is dimensionally tight — important when you later post-process or fit the part onto a fixture. Pairing the resin with the detailed ABS-Like line when you need impact resistance is the natural next step.
Fine-tune these hidden bottom layers and your resin parts will stop peeling, stop gluing to the plate, and come off clean every time. See the full resin lineup at innostation3d.com.