My book is printed in colour but I specified mono.

Find out why mono book files may occasionally be produced using colour-capable printing equipment and how to ensure your files are supplied correctly for mono printing.

On occasion, it may be necessary for mono book files to be printed using colour-capable devices.

Because of this, any files that need to be printed in mono must be supplied as mono files.

This ensures that your artwork is set up correctly for mono printing, regardless of the device used during production.