FlightLineArt

Airliners and warbirds, reduced to single-weight ink

Line weight chart

Which nib for which line

A technical pen set for line art comes in five standard nibs: 0.20, 0.25, 0.35, 0.50 and 0.70 mm. Each one has one job on the plate. Mixing them up is the fastest way to make a drawing that looks fine on the desk and unreadable once it is scanned or printed.

The five-nib chart

Standard technical pen nibs and their role in aircraft line art
Nib size Role on the plate Notes
0.20 mm Hatching / shading Thinnest nib in the set. Needs at least 600 dpi to survive scanning.
0.25 mm Fine panel lines Rasterises to about 3 px at 300 dpi and 6 px at 600 dpi — the reference tier for scan resolution.
0.35 mm Panel lines Standard mid-weight line for access panels and structural breaks.
0.50 mm Outer silhouette Heaviest line most five-pen sets specify for the fuselage and wing outline.
0.70 mm Borders / cover sheets Heaviest nib in a standard set, rarely used inside the drawing itself.

Where lines disappear

A pen weight only matters if it survives the trip from paper to file. The 0.25 mm nib is the useful reference point here: at 300 dpi it rasterises to about 3 pixels, and at 600 dpi to about 6 pixels. Vector exports have the same problem from a different direction — 1 pt equals 0.353 mm, so a 0.5 pt stroke is 0.176 mm, thinner than the thinnest 0.13 mm technical pen most illustrators own.

A 0.25 mm line rasterised at 300 dpi and at 600 dpi, next to a vector hairline and the thinnest technical pen Four horizontal bars of increasing thickness showing a 0.25 mm line at 300 dpi (about 3 px), the same line at 600 dpi (about 6 px), a 0.5 pt vector hairline (0.176 mm), and a 0.13 mm technical pen. 0.5 pt vector hairline, 0.176 mm Thinnest technical pen, 0.13 mm 0.25 mm line at 300 dpi, about 3 px 0.25 mm line at 600 dpi, about 6 px
Figure 1 Relative thickness of a vector hairline, the thinnest common technical pen, and a 0.25 mm inked line scanned at 300 dpi versus 600 dpi. The same physical line nearly doubles in pixel width simply by scanning at 600 dpi instead of 300 dpi, which is why 600 dpi is the working minimum for this chart.

Questions about pen weight

Can I use just two pens instead of five?

You can collapse the chart to three tiers — one heavy for the silhouette, one mid for panel lines, one fine for hatching — but going below three tiers removes the contrast that makes the outline read from the detail at a glance.

Does the 0.70 mm nib ever go inside the drawing?

Rarely. It is the heaviest nib in a standard five-pen set and is normally reserved for borders or cover sheets rather than any line on the aircraft itself.

Why do my scanned lines look thinner than what I inked?

Scan resolution, not the pen. A 0.25 mm line rasterises to only about 3 pixels at 300 dpi. Rescan or re-export at 600 dpi minimum before judging the line weight on screen.