kakeami カケアミ

In manga, kakeami カケアミ is a cross-hatching pattern used to shade objects and backgrounds using lines that form "webs," "nets," ami 網, which are "thrown over" each other, kake 掛け.

For example, in the panel below, the top part of the background features a single kakeami pattern, while the boat is shaded using a gradation of increasing layers of kakeami.

Manga: AQUA (Chapter 5, 希望の丘)

• Design
  
  • カケグラ
  • ナワアミ
• References

Design

The kakeami is a technique used to shade objects using only parallel lines. Generally, this would be called cross-hatching, but kakeami is a bit different from the typical hatching due to how it's drawn.

Hatching is typically done by drawing parallel lines which make something appear darker, and to make it even darker you draw another set of parallel lines perpendicularly. To make it even more darker, you add another set in another direction. And so on.

The kakeami works essentially the same way, but instead of a single line crossing the whole shaded area, each line only crosses a fragment of the whole area, and multiple of such fragments are pieced together to fill the whole shaded area.

Often, lines drawn in one fragment won't cross the lines drawn in another fragment. That is, the fragments don't overlap, even if the lines within each fragment overlap each other.

Source: japanesewithanime.com (CC BY-SA 4.0)

In some cases, they're drawn as overlapping scratches, without border, and in other cases, they're drawn as rectangles with a border.

The word kake カケ is used to refer to how many times the lines overlap. The larger the number of kake, the darker the area becomes.

If there are lines only in one direction, that's ichi-kake １カケ. If lines are added in the perpendicular direction, ni-kake ２カケ. In three directions, san-kake ３カケ, four directions, yon-kake ４カケ, and so on.

At higher numbers, it's hard to tell the pattern is supposed to be made out of lines at all.

This sort of technique was more common in older manga, before screentones became widely used.

With screentones, you can just cut out the pattern you want and paste over the drawing, which is much quicker than drawing the lines individually.

Furthermore, nowadays a lot of artwork is done digitally. In software like Clip Studio Paint, you can add the screentone patterns using a layer mask.

カケグラ

The term kake-gura カケグラ refers to a gradient rendered by transitioning from fewer kake to more kake.

Manga: Gabriel DropOut, ガヴリールドロップアウト (Chapter 3)

• The background of this panel features a kake-gura.

Manga: Bokura wa Minna Kawai-sou 僕らはみんな河合荘 (Chapter 2)

• In this panel, clothes, among other things, are shaded using kakeami.

ナワアミ

This technique can be used to draw a rope in the background by making the rectangle areas align and connect. This is called nawa-ami ナワアミ, "rope net."

Manga: Black Jack, ブラック・ジャック (Chapter 1, 報復)

• ...okuyami wo tsutaete kudasai
  ･･･おくやみをつたえてください
  ...communicate my condolences.
• makoto ni zan'nen desu to
  まことに残念ですと････････････
  [Say] that [it was] truly unfortunate............
  [Say] that [I'm terribly sorry for what happened]............

References

• カケアミ - dic.pixiv.net, accessed 2020-02-27.