Brim vs Raft vs Skirt: Which Bed Adhesion Helper to Use

This comparison is research-based. It draws on slicer documentation from Prusa and OrcaSlicer, not on our own test prints. Treat the numbers below as starting points and adjust for your printer and material.

Brim, raft and skirt are three slicer options that add extra plastic around or under a print's first layer. Only two of them help a part stay on the bed. The short version: a skirt is a primer and a test line, a brim widens the first layer, and a raft builds a separate base under the whole part.

Which one should you use? The quick answer

• Skirt: use it by default on almost every print. It does not touch the part.
• Brim: add it for tall parts with a small footprint, many small parts at once, or materials that curl at the corners.
• Raft: save it for parts that will not stick or sit flat any other way, such as a warped bed, a tiny contact area, or a first layer that needs a smooth base to build on.

What a skirt does

Prusa's documentation describes the skirt as a printed outline of all the models on the bed, printed before any of them. Its main purpose is to stabilize the flow of filament through the nozzle. OrcaSlicer's documentation adds that it primes the hotend and gives a buffer before the model starts.

A skirt is also a free first-layer check. Because it prints first, you can watch it go down and adjust your Z offset live if the line looks too thin and loose or too squashed. Prusa notes that one-layer skirts can be hard to lift off the bed, so its profiles typically use a skirt three layers tall.

The OrcaSlicer wiki says two loops are usually recommended and that extra loops improve priming at the cost of filament and time. Setting loops to 0 turns the skirt off.

Skirt as a draft shield

Both slicers can make the skirt as tall as the tallest object. Prusa describes this draft shield as a way to protect ABS, ASA and similar materials from warping by creating a micro-climate around the part. OrcaSlicer says it is most useful on open-frame printers without an enclosure. If you are choosing between printer types, our guide to enclosed vs open-frame printers covers why this matters.

What a brim does

A brim is a flat ring of extra first-layer lines attached to the outline of the part. The OrcaSlicer wiki describes it as a flat layer printed around a model's base to improve adhesion, useful for models with small footprints or ones prone to warping. Prusa suggests considering a brim before reaching for adhesives, and lists tall objects with a small base and many small objects at once as the cases where it helps.

Brim width and settings

Prusa advises a brim of at least 3 mm to increase adhesion. Wider brims hold more, but they take longer to remove and use more plastic.

• Brim type: PrusaSlicer offers outer only, inner only, or both. OrcaSlicer adds Auto, Painted and Mouse Ears options.
• Mouse ears: small discs placed only at sharp corners, which are the points that tend to lift. This uses far less plastic than a full brim.
• Brim gap: a small gap between brim and part makes removal easier. OrcaSlicer warns that a very large gap reduces the benefit and can remove the contact altogether.
• Per-object brim: PrusaSlicer lets you add a brim to one object only through the object's settings, in Advanced or Expert mode.

What a raft does

A raft is a multi-layer base printed under the part. OrcaSlicer's documentation says it is a base printed under the object to improve adhesion and prevent warping, built from several layers. Prusa's support-material documentation says the object is raised by the chosen number of raft layers and, once printing finishes, you peel the raft away from the part.

Raft options sit in the support settings of both slicers. Key values are the number of raft layers, the contact Z distance (the vertical gap between raft and object, which sets how easily the two separate) and, in PrusaSlicer, raft expansion, which widens the raft in the XY plane for stability.

The downsides of a raft

• It uses the most filament and adds print time.
• The face of the part that sits on the raft will not look like a face printed straight on a smooth plate. Prusa makes the same point about any surface above supports: it will not have the same finish as a side wall or top surface.
• It raises the part, so the object's height in the slicer grows by the raft layers.

When each one makes sense

Choose a skirt if

• the part has a large flat base and your bed is clean and level;
• you want a quick view of the first layer before the part starts;
• you need the nozzle primed so the first line of the model is not thin.

Choose a brim if

• the part is tall and narrow, or sits on a small footprint;
• corners lift on materials that shrink as they cool, such as ABS; see how to fix warping;
• you are printing many small pieces and want them held down together.

Choose a raft if

• nothing else keeps the part on the bed, and you have already checked the first layer and bed cleanliness;
• the bed is slightly uneven and you cannot fix it right now;
• you are printing a tiny contact area, such as a point or a thin edge.

Combining them

The three options are not exclusive. A common arrangement is a skirt with a narrow brim: the skirt primes the nozzle and the brim holds the corners. Note the OrcaSlicer caution that with a draft shield active, the skirt prints at the skirt distance from the object, so it can overlap a brim. Increase the skirt distance to avoid that.

Raft and brim together are rarely needed. A raft already widens the base, and supports built for the part sit on the same stack of layers; see supports explained for how those settings relate.

Removal tips

• Let the bed cool first where the plate allows it. Many plates release parts as they cool.
• A small gap between brim and part makes the brim easier to remove, at the cost of some adhesion benefit, according to the OrcaSlicer documentation.
• The raft's contact Z distance controls how far the raft sits from the object. Both slicers expose it, so adjust it if the raft is hard to separate.

These are general practice points from slicer documentation, not measured results.