Hairlines

What is a Hairline?

A Hairline is a vector path or border styled with an extremely thin stroke width.

In digital design software, lines can be set to “0 pt” or “hairline width”. While these look clear when zooming in on a high-definition monitor, they represent a thickness of less than 0.1 points (approx. 0.03 mm).

For reliable printing, standard lines and borders must be at least 0.25 pt (0.08 mm) thick, and preferably 0.5 pt (0.17 mm) thick.

The Print Risk: Broken Lines and Disappearing Borders

Very thin paths are difficult for commercial printing presses to reproduce:

• Disappearing Borders: When the physical sheet goes through the press, the ink dots for a hairline path may not transfer to the paper at all.
• Jagged or Broken Lines: If ink does transfer, it will appear as a series of disconnected dots rather than a solid line.
• Invisible Graphics: Gridlines in charts, box borders in forms, or separator lines in layouts can disappear completely.

How Filecheck Repairs Hairlines

Catching hairlines before printing prevents customer disputes about missing graphics:

1. Stroke Width Scan: Filecheck measures the stroke thickness of all vector paths in the uploaded file.
2. Flagging Warnings: If any path has a stroke width below the configured threshold (default 0.25 pt), Filecheck flags it.
3. Autofix Thickening: If configured, Filecheck’s remediation engine automatically thickens all hairlines to the minimum printable limit (e.g. 0.25 pt or 0.5 pt). This ensures the lines print clearly as solid, solid boundaries without altering the layout design.