The one-hour rule
Never worked for more than one hour at a time on a single portrait — whether in initial sketch stage or final retouching. After an hour rose, bowed to the client, and dismissed them; the next sitter was prepared in an adjacent room.
Why it matters · Multi-portrait parallel production becomes possible when each session has a hard cap. Drying time is built into the natural gaps between appointments. Painters who let sittings run produce one portrait at a time and starve the studio.
Roger de Piles, Cours de peinture par principes, 1708
Hand the clothing to assistants — keep the head and hands
Painted head and hands from life himself; sketched the costume and posture onto the canvas, then handed the canvas to assistants. The sitter's actual garments were left in the studio for the assistants to copy directly into the painting.
Why it matters · The painter's hand has to be reserved for the decisions that actually require it. Head and hands carry the painting. Painters who execute every inch themselves are spending the master's attention on infrastructure.
Roger de Piles, L'Abrégé de la vie des peintres, 1699
Retain sitters for dinner to observe them off-pose
Often kept sitters for dinner after the session so he could observe them "free from the constraint of posing" — research for what would go into the head and hands at the next sitting.
Why it matters · A held pose is a held face. The dinner is methodological — the painting requires character that cannot be captured during the sitting itself. Same logic Repin would document two centuries later.
Roger de Piles, Cours de peinture par principes, 1708
Two registers — direct for head and hands, glazed for drapery
Head and hands worked in relatively direct, swift opaque colour ("merveilleux promptitude") closer to Hals's alla-prima than Rubens's layered method. Draperies, silks, armor, backgrounds shifted toward the thin luminous glazes of the Venetian tradition.
Why it matters · The painting has different parts requiring different handling. Most painters apply one register to everything. Van Dyck's discipline of switching modes within a single canvas is the cleanest case for matching technique to passage.
Maintain the Iconography as a working reference library
From the mid-1630s onward produced a series of etched portraits of famous contemporaries (the Iconography) — independent work and a reference collection he could pull from for poses, facial constructions, and typologies when planning new commissions.
Why it matters · A painter's previous work is part of the archive. The Iconography is both finished work and ongoing reference. Painters who treat finished work as terminal lose the option to draw on their own vocabulary later.
"Nature is not as she is, but as we think she ought to be"
The portrait was simultaneously a specific likeness and an idealized nobility — the ideal extracted from the sitter, not imposed on them.
Why it matters · The painter's job is to render the sitter accurately as a specific person and to elevate them into the ideal version of that person. The ideal is not invented. It is found in the specific.
Recorded by Roger de Piles, Cours de peinture par principes, 1708