Color by Number Monochrome Mysteries
Simple to start, hard to stop.
100 mystery pages for adults, colored with a single pen.
Every cell holds a number, and every number is a mark: a dot, a slash, a cross, an asterisk, a filled square. You draw them one by one with the pen you already have, no palette and no setup, and a black and white picture slowly rises out of the grid.
What a monochrome color by number page looks like
It starts out as a pale grid of small numbers on white paper, and you cannot tell what it is. Each number asks for a slightly denser mark than the one before, so as the cells fill up, the light and the shadow appear on their own. Then one evening the shape clicks, and you find out what you have been drawing all along.
How it works
There is nothing to plan and nothing to pick. That is what makes it such a relaxing coloring book for adults: you read a number, you draw its mark, you move to the next cell.
Six marks
A dot, then 1 to 5, from the lightest to the darkest. The denser the mark, the darker the cell. The same key runs through the whole book, so you learn it once.
One number per cell
The number is printed in light grey in its cell, and the guide dots show you where each stroke starts and ends. Your mark covers the number, so a finished cell is easy to spot.
One pen
Any pen with a tip around 1mm. No markers to line up, no colors to choose, nothing to carry but the book and the pen.
Why one pen is enough
In a regular color by number book, the shading comes from having many colors. Here it comes from the marks. A field of dots reads as light, crosses read as mid tones, filled squares read as deep shadow, and together they give a black and white picture real depth.
The gesture is closer to cross-stitch than to coloring: small, repetitive, quietly absorbing. And since one pen does everything, the book goes wherever you go.
Free monochrome color by number PDF
The warm-up page is a full monochrome color by number design, a printable PDF with the six marks shown at the top. Print it, grab any pen, and you will know in ten minutes whether the format is for you.
100 Color by Number Monochrome Mysteries
One hundred hidden pictures in a single one color coloring book: animals, portraits, flowers, landscapes and a few surprises.
- 100 mystery pages, printed on one side only
- Six marks, one key for the whole book
- A mark guide and usage gauge on every page
- One pen is all you need, any color you like
- An index with all 100 finished pictures at the end
- Made for fineliners, gel and ballpoint pens. Alcohol markers bleed through
Questions people ask
What is a color by number monochrome book?
It is a mystery coloring book for adults where every number stands for a mark rather than a color. You draw six simple marks in a single color, each one a little darker than the last, and the light and shadow they build reveal a black and white picture you could not see at the start.
How is it different from a regular color by number?
In a regular color by number book, each number means a color and you fill every cell the same flat way. Here each number means a mark, so a single pen is enough to get the full range from white to black. It feels closer to drawing, or to cross-stitch, than to filling shapes.
Which pen should I use?
Any pen with a tip around 1mm: a fineliner, a gel pen or a ballpoint. Black or deep blue gives the classic look. My own favorite is the Uni-ball UM-153. Please skip alcohol markers, they bleed through the paper. The pens I use are listed on the Pixelcolorist links page.
Can I use colors anyway?
Of course. The book is designed for one pen, but plenty of readers give each mark its own color, or switch to sepia, navy or a metallic ink. If drawing the marks in color is the part you enjoy, the book built for it is Hatch & Fill, where every code gives you both the mark and the color.
Is there a monochrome color by number PDF?
Yes, the free warm-up page is a printable PDF, a complete design to try the format. The full book of 100 pages is a paperback, sold on Amazon.
About Éloi
Hi, I'm Éloi. I make coloring books on my own, one at a time, from the first sketch to the last page.
This one came from a simple wish: a mystery book you could finish with nothing but the pen in your pocket. Readers took it further than I expected, some in black, some in sepia, some with a different color for every mark.
I read every message that comes in. If you finish a page, send it over, I love seeing what people do with these.
Where the format comes from
Color by number monochrome, six marks drawn in one pen to build a black and white picture, is a coloring format created by Pixelcolorist and first published on May 15, 2026 in 100 Color by Number Monochrome Mysteries. Its readers then asked for the same marks in color, which became Hatch & Fill.
The book is made and published by Pixelcolorist, and sold on Amazon only. If you come across a lookalike under another name, it did not come from here.