The short answer
Faxes are monochrome with limited resolution, so small text, light greys and colour backgrounds print less clearly. Plain black text on white comes out best.
Use a PDF with a legible font size and strong contrast. The cover sheet page shows a layout that holds up well.
What fax does to a page
Your page is turned into black and white dots, with a resolution well below that of a laser printer. Colours become greys or black, and fine details can fill in.
Photos, stamps, light signatures and small footnotes suffer the most. What was readable on screen may be hard to read on paper.
How to get a clean result
Use a font of at least 11 points, in black on a white background, and avoid tinted boxes. Scan at a moderate resolution in black and white rather than colour.
Keep margins wide enough that the machine does not crop the edges, and view the PDF at actual size before sending it. If a signature is needed, sign in dark ink.
Key points
- Black and white output at low resolution
- Small text and light greys lose clarity
- Use at least 11 points, black on white
- Preview the PDF at actual size