A black and white chalk drawing on blue paper faded to brown, showing the head of a sleeping boy in a cap.

Giovanni Battista Piazzetta produced a great number of these chalk drawings on blue paper of character heads, with one, two and sometimes three heads on the same sheet. His biographers (Albrizzi, Studij di pittura and Dezalier d'Argenville) noted that it was through the sale of these drawings that he was able to sustain his family, and he built up a strong reputation for them. The drawings were always intended to be framed and hung, the consequent exposure to daylight causing the paper to fade from blue to brown.

Although  the models in some of these drawings have been identified (Piazzetta's wife, son and daughter appear several times), they are not intended as portraits of particular sitters. Instead they are often shown with accompanying attributes or with particular facial expressions, operating in the tradition of têtes d'expression. Often the meaning of the attributes is not overt, but the drawings are enigmatic ruminations on age, beauty, innocence and other timeless themes.

All thirty-six of the Piazzetta heads in the Royal Collection, which were hanging at Buckingham Palace until the early twentieth century, must have been acquired as part of the collection of Consul Joseph Smith in 1762. Many of the Piazzetta heads in Smith's collection were engraved by Cattini in 1754 as the Icones ad vivum expressae. The drawings were also copied assiduously by George III's daughters.