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IllustrationBy Prompt TemplateVerified on GPT Image 2 / Nano Banana

Lock the brush, do not name a master

Illustration defaults to plastic AI sheen unless you specify the mark-making. Borrow a trait (“rotating starry strokes”), not a famous name, and cap the palette.

2026/09/01

If you do not name the brush, GPT Image 2 and Nano Banana will pick their house style: even lighting, plastic edges, a gradient sky. If you name a master instead, they will remix a famous composition. Neither is a reusable template.

What actually breaks

We tried “Ghibli-style fox in a library of prompt cards.” Both models quoted a still: the train-on-water angle, the same cloud shapes. Pretty, and not ours. The usable version dropped the studio name and kept the trait: soft watercolor wash, visible paper tooth, pigment pooling in the shadows.

A second failure is an unbounded palette. “Colorful” becomes neon. Four named inks stay still.

The rule we use

  1. Brush first. Watercolor wash, gouache dry-brush, thick oil, ink contour. One verb for how the paint sits.
  2. Steal a trait, not a name. “Rotating starry strokes” instead of “Van Gogh.” “Hayao sky gradients” is still a name — write layered gouache clouds instead.
  3. 4–6 named colors. Lamp black, vermilion, raw sienna, indigo, paper cream.
  4. Composition in one line. Near / mid / far, or “fox large in the foreground, shelves receding.”

Example we actually ran

Weak

Ghibli illustration of a fox librarian with prompt cards, colorful, masterpiece.

Locked

Illustration, not photoreal, not 3D.
Brush: transparent watercolor on cold-press paper, visible tooth, pigment pooling.
Subject: a fox in a linen apron shelving index cards labeled "color", "camera", "copy".
Setting: small library, window light from the left, no famous-film composition.
Palette: lamp black, vermilion, raw sienna, indigo, paper cream. No neon, no plastic sheen.

On GPT Image 2 the paper tooth showed up only when cold-press and visible tooth were both present. Nano Banana needed not 3D render or it mixed a painted fox with a CGI shelf.

When to open this guide from a control

style and brush should change the picture’s substance, not just the adjective. If swapping brush from watercolor to gouache does nothing, the prompt still contains a master name that is winning the argument. Delete the name.

Sources

Rewritten from public pitfall notes; the fox librarian is a Prompt Template example.

Controls this guide covers

  • style

    Name the brush, not a master. “Ghibli” copies a still; “soft watercolor wash” does not.

  • brush

    Lock the mark-making (gouache, ink dry-brush) or you get default AI plastic.

  • palette

    Give 4–6 named colors. Open palettes drift toward neon gradients.