Midjourney prompts that produce clean coloring-book line art

Midjourney can produce publish-quality coloring pages — or muddy gray sketches — depending almost entirely on how you prompt. These patterns come from generating and vector-converting hundreds of pages for real books. Steal them.

The base template

[subject], clean coloring book line art, thick smooth black outlines on pure white background, no shading, no grayscale, kid friendly, full body view

Every phrase earns its place: coloring book line art sets the genre; thick smooth black outlines controls line weight (thin lines break up in print); pure white background stops Midjourney filling the scene with gray texture; no shading, no grayscale suppresses its strongest habit.

What to add per audience

• Toddler books: simple bold shapes, minimal detail, large areas to color
• Kids 6–10: cute cartoon style, moderate detail, friendly expression
• Adult books: intricate detail, elegant flowing linework, decorative background

What to forbid

Put these in the negative/avoid parameters or append as "no …" phrases: shading, hatching, crosshatch, stippling, grayscale fill, solid black areas, watermark, text, signature. Solid black fills are the sneakiest failure — they look striking as thumbnails and terrible as coloring pages, because there is nothing left to color.

Fixing the common failures

Gray, sketchy lines

Strengthen with bold ink drawing, uniform line weight. Remaining light gray disappears in vector conversion — that pass forces every pixel to pure black or pure white.

Backgrounds full of texture

Add plain white empty background and, for subjects that need context, simple minimal background elements. Busy texture becomes unpleasant noise after thresholding.

Broken outlines

Some styles draw fashionably interrupted lines. They frustrate anyone coloring digitally (fills leak) — ask for closed continuous outlines and spot-check pages by flood-filling a region in any paint app before publishing.

Consistency across a whole book

• Reuse one exact style phrase in every prompt of the book.
• Use Midjourney's style-reference / seed features on a page you love and generate the rest against it.
• Generate 20% more pages than you need and cut the outliers — cheaper than fixing them.

Finish every page with the free vector converter so the printed lines are pure black at any size — the difference between "homemade" and "professional" on paper.