Please help to identify this map-printing technique

Question

Most old maps in my home (ranging from a school atlas to professionally made large maps from the National Atlas of India) use a peculiar technology. Instead of colored 'dots', they use 'strokes' of continuous, straight lines oriented in different directions.

The following image is a portion of a map of South America from a school atlas published by a local publisher here in Kolkata (Chandi Charan Das and co., 150 Lenin sarani, kol-13. No mention of date or edition found, but it is a 15 to 20 year old book).

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Scale:

The word Caracas ( "কারাকাস" ) on paper is approximately 1.05 cm wide.

On a compound microscope (biology) (objective: 10X, eyepiece: 10X) but using reflected light, the lines do not show any 'dots' but instead uniform, continuous bands. The photograph below is taken from another map (on Asia, topography) from the same book.

The image on the left shows some vertical and horizontal lines. The one on the right shows some diagonal lines.

However the same school atlas also uses dot printing. There are also other maps which are solely made from dots, without any of these 'solid' lines.

An old map by the National Atlas of India, copyrighted in 1986, uses a similar pattern and probably the same technology. However, their grids are finer (narrower and more closely placed).

Scale:

The width of the word "Chamoli" on paper is approximately 3.3 cm.

Could anyone help me identity this beautiful, old map printing technology?

Answer 1

At its heart, this is simply called "line art," and as DA01 states, halftone dots are really just a method to get a continuous tone (photograph etc) into line-art form for printing with a single ink.

Map makers are usually free to choose the tones they use, but in some case, such as geological survey, the texture choices are formalized so as to represent different types of rock etc.

In the mid-late 20th century, maps, comics and manga often would be shaded by using a sheet of pre-made texture cut into the desired shape and then compositing them, like a collage.

A company called Letraset (above) used to sell rub-on transfers which people would xerox, cut, and paste, and people would often buy a set and then xerox them infinitely.

If this reminds you of old video games from the 80s and 90s, well, some of those artists had to use these real-world materials in their technical drawing classes.

For manga, the artists would ink the lines with pen, and then use "screen tones" for the shading. These were often then photographed "as-is" without the need of a halftone screen.

The image below shows the use of screen tones by Katsuhiro Otomo, along with some examples of screen-tone texture sheets. The artist cut, overpainted and/or scratched away some of the screen.

Answer 2

It's not particularly a technology nor something exclusive to maps. It's essentially doing the same as your 'dots' method--which is screening back a solid color via a pattern. The only difference here is that instead of a dot pattern, they're using lines...what you could consider a modern form of hand-drawn line work referred to as hatching (or the more commonly heard variant: cross-hatching)

This old map here uses hatching to emphasize the water edge:

When using multiple colors, you also end up with the useful side-effect that my layering different layers down with or without hatching, you get the multi-color printing capability of mixing colors on page.