Woodcut by  Albecht Dürer

The net frame is a drawing aid consisting of a frame in which stronger threads (twine) are stretched in such a way that they form a grid of square fields. This squaring was already known in antiquity. Albrecht Dürer recommended the size of the squares two fingers wide. On the drawing level (paper), the same division is used with the drawing pen, very fine.
The artist now transfers square by square from nature to the drawing plane. He works two-dimensionally by closing one eye and always aiming at a certain fixed point through the grid. For this reason Dürer used a sighting device (see woodcut) to find the exact viewing distance and angle once selected.

Leonardo da Vinci recommended to place a small wax ball at the intersection of two threads. With the mesh frame, one can also enlarge or reduce by simply drawing the squares on the drawing plane (paper) larger or smaller.

The squaring was often used in the creation of the cardboard in fresco painting. Here, a small-format design is transferred to a large-format "cardboard "*. This was then traced 1:1 on the still fresh wall plaster by rubbing paint powder on the back of the cardboard and then tracing the outlines of the drawing with a pen (stylus).

In miniature painting, the design of a drawing is transferred from normal size to a very small square grid.

The use of a net frame was already recommended in 1435 by L. B. Alberti (1404-1472) as an aid in order to correctly capture the perspective shortenings and bevels in paintings.

Drawings with squaring

*Cartoon (fine art) = This is not a thick cardboard as we know it, but rather:

Several sheets were glued together with ordinary, usually also cheap thin drawing paper with glue, since there were no large-format papers in former times. This large paper is called "cartoon". After the work was done, the cardboard was usually destroyed.