A PDF watermark is not "copy protection" -- screenshots and OCR defeat it every time. Its job is to mark the source and the responsible party, so whoever holds the file can tell whose copy it is.
1. What to put in the watermark text
- Recipient name: for example "For XX Company only", so a leak can be traced to one recipient;
- Usage restriction: "For tender submission only, do not forward";
- Date and reference: "2026-10-22 / internal ref A-017", which also helps version control;
- Do not include: ID numbers, phone numbers or other personal data -- the watermark itself becomes a leak.
2. Opacity and placement
Use light grey (about 25% visual weight) and a diagonal tiled pattern at 45 degrees. Too light and nobody sees it; too dark and it hurts reading and printing. Add a PDF watermark lets you set the text and opacity, and tiles diagonally by default.
A single mark in one corner buys you very little -- crop the margin and it is gone. Tiling matters because every partial screenshot still carries the mark.
3. Watermarking makes the file bigger
The watermark is written into every page as a text object and forces the PDF to be re-saved. A tightly compressed file can grow 20-50% after watermarking. Recommended order: watermark first, compress second, so the compression also clears the overhead the watermark introduced.
4. A watermark is not encryption
If you need to actually block opening or printing, you need PDF permission passwords, which require professional tools. A watermark is social protection: it makes forwarding feel costly and tells the recipient that the file has an owner.
5. Send a different version to each recipient
Quoting the same job to three clients is safest with three different watermarks, one per client name. If a copy shows up elsewhere, you know immediately who shared it. In batch cases, export once per client name -- far easier than investigating afterwards.