How Did They Copy a Drawing Before Tracing Paper? Prick It and Dust It
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Transferring a full size drawing onto a wall or panel was done by pricking holes along every line and pushing powder through them, which leaves a trail of dots to follow.
How the method works
A drawing made at full size on paper has fine holes pricked along all of its lines with a needle, at intervals of a few millimetres. The sheet is held against the surface to be painted, and a small cloth bag of fine powder, usually charcoal or chalk dust, is patted over it. Powder passes through each hole and leaves a dot on the surface beneath. Lifting the sheet reveals the whole design as a dotted outline, which the painter then joins up with a brush or a chalk line before beginning work.
Why it was necessary
The alternatives were worse for the situations it was used in:
- •A wall cannot be drawn on and corrected freely
- •Fresco plaster must be painted while wet, leaving no time to design
- •A design approved by a patron had to be reproduced exactly
- •The same design might be needed several times over
- •Assistants could transfer while the master worked elsewhere
- •Paper was expensive, so one drawing had to serve repeatedly
What it tells conservators
The traces left by the process are among the most useful evidence available about how a painting was made. Infrared imaging reveals the dotted underdrawing beneath the paint, and the pattern of dots distinguishes this method from freehand drawing and from lines incised into plaster. Comparing the dots against a surviving full size drawing can confirm that the two belong together. Finding the same dotted pattern in two different paintings proves the same drawing was used twice, which is direct evidence of workshop practice, of copying and occasionally of forgery.
The full size drawings themselves
The sheets used for this work are objects of considerable importance in their own right and very few survive. A full size drawing for a large fresco could run to many square metres of paper joined together, and it was treated as a working tool rather than as a finished artwork, so it was pricked, dusted, folded, reused and eventually discarded. The handful that survive are among the most studied drawings in existence, since they show the design at the stage immediately before execution, complete with the changes made after the first version was approved.
The wider family of transfer methods
Several techniques did the same job and each leaves its own signature. Squaring involves drawing a grid over the original and a matching grid at larger scale on the surface, then copying square by square, which allows enlargement and leaves faint grid lines. Incising presses a stylus along the lines of a drawing laid on wet plaster, leaving grooves that survive under the paint. Carbon transfer blackens the back of a sheet and traces over the front. Each was chosen for the surface and the scale at hand, and traces of all of them survive in Renaissance work.
The takeaway
Pricking holes along the lines of a full size drawing and dusting powder through them leaves a dotted outline on the surface below, which was essential where fresco plaster had to be painted wet and a design could not be worked out in place. Infrared imaging reveals the dots, and matching patterns in two paintings prove one drawing served both.