PDF toolsWatermarks do one of two jobs. Either they communicate a status (DRAFT, CONFIDENTIAL, SAMPLE), or they discourage reuse by making a document traceable or unattractive to copy. The first job needs readability; the second needs coverage. Decide which one you're doing before choosing the settings.
Settings that work
- Opacity: 15 to 30 percent. Above that, the watermark starts competing with the text. Below 10 percent it disappears when printed on a cheap printer.
- Angle: 45° for a single mark. Diagonal text crosses lines of body text rather than sitting on top of one line, which keeps the page readable.
- Colour: grey or a muted red. Pure black at low opacity looks like a printing fault.
- One or two words. "CONFIDENTIAL" works. "Confidential – do not distribute outside the finance team" doesn't; put that sentence in a footer.
In Watermark, the defaults (64 pt, 25 percent, 45°) follow these rules. Change the text and press Add watermark.
Single mark or tiled?
A single large mark is enough for status. If you're sending a sample that you don't want reused, tick Repeat across the page: a tiled pattern is much harder to crop out or paint over, and it survives screenshots of part of a page.
For traceability, put the recipient's name in the watermark ("Prepared for J. Martin"). People are less likely to forward a document with their own name across every page.
When a watermark is the wrong tool
- For an approval status on a single page, a stamp (APPROVED, PAID) reads more naturally and doesn't cover the content.
- For legal or version information, a header or footer is cleaner and stays out of the way.
A reality check
A watermark added to a PDF is drawn into the page, but anyone with a PDF editor and some patience can remove it. It's a deterrent and a label, not security. For documents that truly must not leak, don't send them as PDF attachments at all.