Mark sharp edges

Mark edges that should preserve a hard shading boundary. This changes edge attributes, not the silhouette or topology.

Before you start

Use Edge Select in Mesh Edit Mode. Sharp marks define shading boundaries without cutting the mesh apart.

Keep a deliberate hard shading break along selected edges.

Select the edges along the rim, seam, or corner that should read as a hard boundary.
Open the edge context menu and choose Mark Sharp.
Inspect the surface under smooth shading. Choose Clear Sharp on the same edges if the split is too strong.

Controls	What changes
Mark Sharp	Stores a hard boundary on the selected edges. It does not create a bevel or add support loops.
Clear Sharp	Allows smoothing across those edges again, subject to the surrounding face and material behavior.
Flat surfaces	A sharp mark can be hard to distinguish when all faces are already shaded flat. Inspect the intended smooth-shaded result.

The marked boundary should be crisp while adjacent curved areas remain smooth. Use Bevel when the silhouette needs a real rounded edge.

Open the editor and follow the steps with your own scene.