Before beginning a cartoon, Raphael and his assistants would have created small-scale sketches known as modelli. Here, they worked out the basic design and experimented with composition before starting on the cartoon itself.
Constructing cartoons of this size presented a considerable technical challenge. Each cartoon is not one vast sheet of paper, but many small square sheets stuck together with a flour-and-water paste. This X-ray photograph shows the places where the sheets were glued together. The resulting patchwork would have been hung up for painting.
Raphael and his assistants painted the designs with distemper, a mixture of pigment, water, and animal glue. The distemper is laid on very thickly in places, and drips are visible upon close examination. When the cartoons were finished to Raphael's satisfaction and the distemper had dried, they were sent to the tapestry weavers' workshop, where they were cut into one-yard-wide strips and distributed to the weavers. Each weaver placed a strip beneath his loom and used it as a guide for weaving that particular section of the tapestries. The separately woven sections were then sewn together.
The cartoons were reassembled in the late 1690s, during the reign of William III. By this time, they had become extremely fragile, and they had to be glued to a canvas backing. The joins, which are not always even, are still visible in X-rays. Raphael's cartoons are unusual in their degree of detail and finish. Typically, tapestry cartoons were not quite as highly detailed, and the weavers were allowed to fill in missing details as they saw fit.
Raphael also used an extremely subtle colour palette, one which the weavers would not have been able to reproduce exactly. This suggests that Raphael may have considered the cartoons to be works of art in their own right, rather than designs for another work. However, he may simply not have wanted the cartoons to leave his workshop in an unfinished state. In any case, centuries after their creation, the cartoons have come to be considered independent works.