I routinely transfer designs as I rework subjects in various mediums. There are several standard methods for transferring designs to a target surface.
One long-used method was to prepare a cartoon to the exact dimensions of the target wall or canvas. Once the design was fixed, it would be transferred by one of the following methods:
- Covering the back of the cartoon with charcoal or some similar material, then tracing over the design with enough pressure to transfer the charcoal to the surface. This method treats the cartoon as a giant piece of carbon paper.
- The design’s lines would be perforated with holes, then charcoal rubbed over the lines with enough pressure to force the charcoal through the holes.
While still used for large pieces, such as murals, these methods have significant drawbacks. First, the cartoon has to be the same size as the target surface. Second, the process would (most likely) destroy the cartoon.
Another oft-used method was to use some type of optical device, such as a projector or camera obscura, to project an image onto the surface. David Hockney, in his book Secret Knowledge, demonstrated that this method was used from the early Renaissance. Projectors are now ubiquitous, of course.
Another widely used method, and the one I prefer, is to use a grid. The design is divided into a regular grid, which is repeated on the target, then the design is recreated on the canvas.
The grid enables me to revisit the drawing as I enlarge it on the canvas. I value being able to rework the design as I go. For me, using a projector short-circuits this important activity. In the past, I sometimes used one for large oil paintings, but now I only use a projector for large watercolors. Reworking is not compatible with fussy watercolor paper.