ZBrush Tip: Protect Seam Integrity with Edge-Loop Masking

Protect seam integrity while smoothing by masking edge loops. This workflow helps you polish surfaces without collapsing clothing seams, panel splits, or hard edges.

• Goal: Create a narrow, reliable “safety belt” mask around seam edges so smoothing operations don’t round them off.
• Applies to: clothing seams, hard-surface panel lines, UV seam borders, boolean cuts, and retopo border loops.

1. Prep clean seam borders
   • Assign Polygroups around the seam: Tool > PolyGroups > Group By Normals (tune Max Angle), or slice with SliceCurve (Groups enabled).
   • If needed, add supportive loops: Tool > Geometry > EdgeLoop > GroupLoops. Typical settings: Loops 1–2, Polish 0–10, Coverage 5–10. This gives you tidy edge rings to mask.
2. Auto-mask the seam
   • Tool > Masking > Mask By Feature: enable Groups and Border, Intensity 100 to catch polygroup borders and open edges.
   • Widen the protective band: use GrowMask 1–2 times, then SharpenMask for a crisp edge. Tip: Ctrl+Click on the model blurs the mask; Ctrl+Alt+Click sharpens.
3. Smooth without loss
   • Use Shift-smooth normally; the masked ring prevents edge roll-off.
   • For global operations, try Deformation > Smooth or Polish By Features (respects groups) to keep panel definition intact.
   • Invert the mask (Ctrl+Click on empty canvas) when you need to smooth inside panels while guarding the seam.
4. Make it reusable
   • Convert the mask to a Polygroup: Tool > PolyGroups > Group Masked. Now you can isolate or re-mask it in one click.
   • Before subdividing, apply Geometry > Crease > Crease PG or CreaseByPG to preserve those edges through higher Subdiv levels.
5. Quality checks
   • Toggle PolyFrame (Shift+F) to verify loop continuity and density before smoothing.
   • If projection or remeshing is planned, enable ZRemesher > KeepGroups so borders remain crisp.

Pro tips

• Combine Mask By Cavity with Mask By Feature to protect both seam rims and deep creases during broad smoothing passes.
• For cloth: lightly smooth first, then use Inflate brush along the seam (low ZIntensity) to restore body without flattening stitching.
• When you need ultra-stable edges, place two narrow GroupLoops and mask both—this “double belt” resists aggressive smoothing.
• On asymmetric pieces, enable Transform > Local Symmetry so operations respect local pivoting around irregular seams.

Why it works

• Border-aware masking isolates high-contrast topology transitions where smoothing artifacts are most visible.
• GroupLoops create even edge rings that respond predictably to smoothing and polishing tools.

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