A brim in 3D printing is a flat layer of material printed around the base of your object on the first layer, directly attached to its edges. Think of it like the brim of a hat: it extends outward from the bottom of your part, increasing the surface area gripping the build plate. Its main job is to prevent warping and keep your print stuck down during the entire job.
How a Brim Works
When hot plastic cools on the build plate, it contracts. That contraction pulls the edges of your print upward, which is what causes warping, especially at corners. A brim counteracts this by giving the first layer a much larger footprint than the object itself. The extra surface area holds the edges flat against the plate, and any curling that does happen transfers into the brim rather than into your actual part.
A brim is always one layer tall and prints only on the first layer. It attaches directly to the outer edge of your model’s base, so it’s physically connected to the part until you remove it. This direct connection is what gives it real holding power compared to other adhesion helpers.
Brim vs. Skirt vs. Raft
Most slicers offer three adhesion options, and the differences are straightforward:
- Skirt: A perimeter line printed around your object but not touching it. It doesn’t help with adhesion at all. Its real purpose is to prime the nozzle and let you visually check that the first layer is going down correctly. Use it when you don’t expect sticking problems.
- Brim: A flat perimeter that connects directly to your part’s first layer. It adds moderate adhesion without much extra material or print time. It’s often considered the best all-around choice for prints prone to warping.
- Raft: A full multi-layer platform printed underneath your entire object. It provides the strongest adhesion because plastic sticks best to plastic, but it uses significantly more filament, adds more print time, and leaves a rougher texture on the bottom of your part.
A brim sits in the sweet spot. It gives you meaningful adhesion while keeping material waste and print time low. If you also care about the look of your print’s bottom surface, a brim leaves it much cleaner than a raft would.
When You Need a Brim
Not every print needs one. Small PLA objects on a level, heated bed typically stick fine on their own. But certain situations make a brim close to essential.
Materials with high shrinkage rates are the biggest reason to use a brim. ABS is the classic example: it contracts aggressively as it cools and will peel off the bed without extra help. Nylon and other high-temperature filaments behave similarly. Even PLA can warp on very large or dense prints, though it’s uncommon on a properly leveled plate.
Geometry matters too. Models with large flat surfaces and sharp corners are especially prone to lifting at those corners. Tall, narrow objects with a small base footprint also benefit from the extra stability a brim provides. If your print has thin sections touching the build plate, a brim can prevent those fragile contact points from popping loose mid-print.
Typical Brim Settings
In most slicers, you control a brim primarily through its width or line count. Prusa’s documentation recommends at least 3 mm of brim width to meaningfully improve adhesion. Many users go wider for large or warp-prone prints, sometimes up to 10 or 15 mm. In Cura, you’ll set this as a number of brim lines rather than millimeters, but the idea is the same: more lines means a wider brim and a stronger grip.
There’s also a setting called brim offset (or gap) that controls how close the brim sits to your part. The default is 0 mm, meaning the brim is fused directly to the model’s edge. If you find the brim is too difficult to remove cleanly, bumping that offset to 0.1 or 0.2 mm creates a tiny gap that makes separation easier while still providing most of the adhesion benefit.
Removing a Brim
Because a brim is only one layer thick and attached at the edge of your part, removal is usually simple. For most prints, you can peel it off by hand or with a pair of pliers once the print cools. If the brim is thin and well-adhered, a craft knife or deburring tool works well. A deburring tool is safer and faster for sweeping along the edge, while a craft knife gives you more precision in tight spots but carries more risk of digging into the part itself.
After peeling, you may notice a slight ridge or rough edge along the base where the brim was attached. Light sanding with fine-grit sandpaper cleans this up in seconds. If you’re printing something where the bottom edge needs to look perfect, consider using a small brim offset to make the connection weaker and the cleanup easier.
When to Skip the Brim
A brim isn’t always the right call. If dimensional accuracy at the base of your print matters, the connection point between brim and part can leave a slightly uneven edge that’s hard to sand perfectly. For parts that need to fit together precisely at the first layer, printing without a brim (or using a skirt instead) avoids that issue entirely.
If your adhesion problems are severe enough that a brim still doesn’t hold, a raft is the next step up. Rafts are overkill for most prints, but for extremely warp-prone materials or prints with almost no base contact area, they give the strongest possible grip on the build plate.