Adhesion in 3D printing refers to how well melted plastic sticks to surfaces, both the build plate underneath and the previously printed layers above. It comes in two forms: bed adhesion (the bond between your first layer and the print surface) and interlayer adhesion (the bond between each successive layer of your print). Both types are critical. Poor bed adhesion causes prints to detach or warp mid-print. Poor interlayer adhesion produces weak parts that crack or delaminate under stress.
Bed Adhesion: Why the First Layer Matters Most
When your printer extrudes the first layer, semi-molten plastic needs to grip the build plate firmly enough to anchor the entire print. This bond is created by a combination of three things: the filament type, the build surface material, and the bed temperature. Get any one of these wrong and the print will pop loose, sometimes minutes in, sometimes hours into a long job.
As each new layer is deposited, the plastic below it cools and contracts slightly. A single line of cooled filament doesn’t generate enough force to break free from the plate, but those forces accumulate as the print grows taller. Sharp corners are especially vulnerable because shrinkage forces from two edges converge at the same point, creating stress concentrations that peel the corners upward. This peeling is called warping, and it’s the most common adhesion failure in 3D printing.
How Warping Happens
Warping is fundamentally a temperature problem. Heated plastic expands; cooling plastic shrinks. When your printer lays down filament at 200°C or more and that filament cools to room temperature, it wants to get shorter. Multiply that contraction across thousands of lines and dozens of layers, and a thermal moment forms around the edges of the part, pulling corners and edges upward off the bed.
Parts with large flat footprints and sharp corners are the worst offenders. Round shapes distribute stress more evenly and warp less. Materials also vary dramatically: ABS is notorious for warping, while PLA barely shrinks at all. This is why the recommended bed temperatures differ so much between materials. PLA prints well at 45 to 60°C, PETG needs 75 to 90°C, nylon requires 70 to 90°C, and ABS demands 95 to 110°C. Higher bed temperatures keep the bottom of the part warm enough that it doesn’t contract as aggressively against the plate.
Build Surface Options
The material your build plate is made from has a huge impact on adhesion. PEI sheets (sometimes sold as spring steel sheets with a PEI coating) offer strong natural adhesion to most filaments without any glue or spray. They’re the most popular surface for general-purpose printing. However, nylon, polypropylene, and some high-performance plastics still need glue even on PEI.
Glass beds are smooth and flat but have almost no natural grip. PLA sticks reasonably well to clean glass, but most other materials need an adhesive layer. Glass also carries a risk of damage: some filaments bond so strongly during printing that chunks of glass get pulled out when the part cools. PETG is particularly bad for this and should never be printed directly on bare glass.
Garolite (G10) is a niche surface that works well with nylon, a material that’s notoriously difficult to stick down. It doesn’t match PEI’s all-around adhesion, but for nylon printing specifically, it’s a strong choice. Carbon fiber reinforced spring steel sheets look impressive but have almost no natural adhesion to anything and always require glue.
Adhesives and Surface Treatments
When your build surface alone isn’t enough, a thin adhesive layer bridges the gap. The two most common options are glue sticks and hairspray. Glue sticks (the purple, washable kind) create a tacky layer that grips filament during printing and releases when you flex a spring steel plate or use a scraper. They work with nearly all materials on all surfaces.
Hairspray works through copolymers in its formula, compounds originally designed for light, heat-resistant adhesion on hair that happen to perform the same function on a print bed. The key ingredient to look for is vinyl neodecanoate copolymer. Hairspray works well for PLA and ABS but poorly for PETG, and it doesn’t help at all with nylon or other engineering plastics. The overspray can also be messy, coating nearby surfaces over time.
With any adhesive, less is more. Too thick a layer creates uneven patches that affect auto-leveling accuracy and leave a rough, lumpy bottom surface on your prints. Reapply in thin coats and clean the bed periodically to avoid buildup.
Slicer Settings That Improve Adhesion
Your slicer software offers three features specifically designed to help with bed adhesion: skirts, brims, and rafts.
- Skirts are outlines printed a few millimeters away from your part. They don’t touch the model at all. Their purpose is to prime the nozzle and let you visually inspect the first layer for leveling or adhesion problems before the actual print begins.
- Brims are flat rings of plastic printed directly against the edges of your part, extending outward like the brim of a hat. They increase the surface area gripping the bed, which holds down edges and corners that would otherwise warp. Five or more outlines is typical. If the brim bonds too tightly to the finished part, adding a tiny gap of 0.1 to 0.2mm between the brim and the model makes removal easier.
- Rafts are full platforms printed underneath the entire model, with a small air gap (usually around 0.1mm) separating the raft from the part. Rafts are most useful for ABS prints prone to warping or for models with very small footprints that don’t have enough contact area to stay anchored on their own.
First Layer Calibration
No adhesive or slicer trick compensates for a badly calibrated first layer. If the nozzle is too high, filament lands on the bed without being pressed into the surface and won’t stick. If it’s too low, the nozzle scrapes the bed and blocks extrusion. The goal is a first layer that’s slightly squished flat, with adjacent lines fusing together into a smooth, continuous sheet.
A common recommendation is to set first layer height equal to the nozzle diameter (for example, 0.35mm for a 0.35mm nozzle) and first layer extrusion width to roughly 200% of the layer height. That wider extrusion pushes more plastic against the bed, creating a broader contact patch. Most slicer software labels these settings clearly and lets you adjust them independently from the rest of the print.
Interlayer Adhesion: Strength Between Layers
Bed adhesion keeps the print stuck down. Interlayer adhesion determines how strong the finished part is. Every 3D printed object is built from stacked layers, and the boundaries between those layers are the weakest points in the structure. A part might look solid but snap cleanly along a layer line under force.
Layer height is the single biggest factor. Research on 3D-printed composites found that reducing layer height from 0.4mm to 0.3mm roughly doubled shear strength, jumping from around 6 MPa to 12.5 MPa. Thinner layers mean the hot nozzle passes closer to the previous layer, reheating it enough to form a stronger molecular bond. Line width also matters: narrowing the extrusion width from 1.2mm to 1mm increased shear strength by about 43% in the same tests. Between the two variables, layer height has the larger effect.
Temperature plays a role here too. If the extruded plastic cools too quickly before the next layer arrives, the bond between layers suffers. Printing in a cold room or near an air vent can weaken interlayer adhesion noticeably, especially for materials like ABS that are sensitive to temperature swings.
How an Enclosure Helps
An enclosure around your printer addresses both types of adhesion at once. By trapping heat and blocking drafts, it keeps the air temperature around the print consistent. Different parts of the model cool at roughly the same rate, which reduces the uneven shrinkage that causes warping and bed adhesion failures. For ABS, an enclosure can be the difference between a print that peels off the bed and one that stays perfectly flat.
Enclosures also improve interlayer adhesion by keeping previously printed layers warmer when the next layer arrives, giving the plastic more time to fuse at the boundary. This matters less for PLA, which prints at lower temperatures and barely warps, but it’s significant for ABS, nylon, and polycarbonate. If you’re printing exclusively in PLA, an enclosure is optional. For engineering materials, it’s close to essential.