The first layer is the foundation every other layer is built on. If it is squished evenly, bonded to the plate, and free of gaps, the rest of the print usually takes care of itself. If it is high in one corner, peeling at a thin tip, or laid down as loose spaghetti, no amount of clever slicing higher up will save the part. This guide covers the mechanical settings, the surface preparation, and the geometry choices that together produce a first layer you can trust on nearly every print.
First layer height, width, and the nozzle gap
A good first layer is deliberately over-squished. Where interior layers might be 0.2 mm tall, a first layer prints best at roughly 75–100% of nozzle diameter and is pressed firmly into the plate so the extrudate spreads and keys into the surface texture. The distance between the nozzle tip and the bed – the nozzle gap – is set by your Z offset or by paper-gap leveling, and it matters more than almost any other single value.
If the gap is too large the lines stay round, barely touch each other, and lift as they cool. If it is too small the nozzle plows into the plate, leaves ridges, and can clog from back-pressure. Aim for lines that are slightly flattened ovals with their edges just merging into their neighbors, leaving no visible valley between passes.
| Symptom | Likely cause | Fix |
|---|---|---|
| Gaps between first-layer lines | Nozzle too high or width too low | Lower Z offset; raise first-layer width to 110–140% |
| Translucent, scraped, or ridged lines | Nozzle too low | Raise Z offset in 0.02–0.05 mm steps |
| Corner lifts after a few layers | Uneven gap or cold spot on plate | Re-level; raise bed temp 5–10°C |
| Lines ripple or wave | First layer too fast | Drop first-layer speed to 15–25 mm/s |
Set your first layer height at or above the layer height you print with, never below it. A 0.12 mm first layer on a 0.4 mm nozzle leaves almost no room for bed variation and turns small leveling errors into failures.
Leveling and bed prep
Leveling – whether manual with a sheet of paper, or automatic with a probe and mesh – establishes a consistent gap across the whole plate. Automatic bed meshing compensates for a warped or tilted surface, but it cannot fix a dirty one. The most common adhesion failure is not leveling at all; it is oils. Fingerprints, mold-release residue on new sheets, and a haze of skin oil build up invisibly and repel the first layer.
Clean the build surface with warm water and dish soap, then a final wipe with isopropyl alcohol once it is dry. Handle the plate by its edges afterward. Different surfaces then reward different habits:
| Surface | Best for | Notes |
|---|---|---|
| Textured PEI | PLA, PETG, TPU | Grippy matte bottom finish; PETG can over-adhere, so a thin glue-stick layer acts as a release |
| Smooth PEI | PLA, ABS, ASA | Glossy bottoms; degrease often as it loses grip when oily |
| Glass | PLA, ABS with a slurry | Very flat; needs glue stick, hairspray, or a PVA slurry for grip |
| Garolite / FR4 | Nylon (PA) | One of the few surfaces nylon bonds to reliably |
For stubborn materials, a thin, even film of PVA glue stick does two jobs at once: it boosts adhesion while warm and acts as a release agent so the part pops off cleanly when the plate cools.
Skirts, brims, and rafts
These three helpers are often confused. A skirt is a loop printed around the part but not touching it; its only job is to prime the nozzle and let you confirm the gap looks right before the real perimeter starts. A brim is a flat collar of extra perimeters fused to the base of the part, adding footprint and resisting lifting – ideal for tall, narrow, or spindly models. A raft is a full multi-layer platform the part prints on top of, useful for warp-prone materials or badly worn plates, at the cost of material, time, and a rougher bottom face.
Reach for a brim first; it solves most adhesion and warping problems with far less waste than a raft. Five to eight brim loops (roughly 4–6 mm) is plenty for most parts. Save rafts for materials like ABS on a marginal surface, or geometry with tiny contact points.
First-layer speed and temperature
Slow down. Interior layers may fly at 150 mm/s and higher, but the first layer should crawl at 15–25 mm/s so molten plastic has time to wet and key into the surface. Run the bed at the material’s recommended temperature – around 55–60°C for PLA, 70–80°C for PETG, and 90–110°C for ABS or ASA – and keep part cooling fans off for the first layer so it stays hot enough to bond. Turning the fan on too early is a frequent, hidden cause of corner lift.
Elephant foot: causes and fixes
Elephant foot is the bulge at the very bottom of a print where the first few layers splay outward wider than the model. It comes from the combination of a heated bed keeping the base soft and the weight of layers above squashing it, made worse by an over-low nozzle gap. It is a dimensional problem too: a hole or peg that must fit a mate will be undersized or oversized right at the base.
The cleanest fixes are a small elephant-foot compensation (many slicers offer 0.1–0.3 mm, which trims the outer wall of the bottom layers), a slightly higher Z offset, and a bed no hotter than it needs to be. A 45° chamfer of about 0.4–0.8 mm modeled onto bottom edges also hides the bulge and gives a cleaner seat. If your bottom edges must be dimensionally exact, treat this the same way you would any fit – see our tolerances guide for how much clearance to design in, and our wall thickness guide for base features that will not distort.
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- Degrease the plate with soap and water, then isopropyl alcohol; handle it by the edges only.
- Level the bed or run an auto mesh, and set first layer height at or above your normal layer height.
- Set the Z offset so lines are flattened ovals that merge with no visible gaps.
- Slow the first layer to 15–25 mm/s and turn the part cooling fan off for layer one.
- Set bed temperature to the material spec; nudge it up 5–10°C only if corners lift.
- Add a brim for tall or spindly parts; reserve rafts for warp-prone materials.
- If you see elephant foot, apply 0.1–0.3 mm compensation, raise the Z offset slightly, or chamfer the base.
- Watch the first layer print before walking away – it is the cheapest failure to catch early. New to the fundamentals? Start with Foundations.