Watermarks are drawn onto the page as content. That makes them permanent in your copy and removable by anyone with an editor.
Use them to communicate status: draft, confidential, sample, the recipient's name. Do not use them as a security measure, because they are not one.
The classic diagonal DRAFT across a page does a real job. It stops someone circulating a version that was not final, and it makes the document's status obvious at a glance rather than buried in a covering email nobody reads.
What a watermark actually is
Text or an image drawn onto each page, usually at reduced opacity and often rotated. Technically it is no different from any other graphic on the page, which explains both its strengths and its limits.
Because it is page content, it prints, it survives being sent anywhere, and it appears in every reader without depending on annotation support. Because it is page content, it can be removed by anything that can edit page content.
Drawn onto the page like any other text or graphic.
No dependency on the reader supporting a separate layer.
Removable by anyone with an editor, in a couple of minutes.
Keeping the document readable
The usual mistake is a watermark so assertive that the document underneath becomes hard to read, and the usual cause is opacity.
A watermark exists to be noticed rather than to dominate. Somewhere between ten and twenty percent opacity is legible as a mark and stays out of the way of the text. Above thirty it starts competing with the content, and at full opacity it is not a watermark, it is a redaction with a friendly name.
- Opacity10 to 20 percent
- Rotation45 degrees diagonal
- ColourGrey rather than black
- PositionCentred on the page
- SizeLarge, spanning the page
- LayerBehind the text where possible
What watermarks are good for
Three uses account for nearly all sensible watermarking, and all of them are about communication rather than control.
Marking status
DRAFT, FOR REVIEW, SUPERSEDED, NOT FOR CIRCULATION. The most valuable use, because it stops honest mistakes: someone finding an old file and acting on it as if it were current.
Marking ownership
A company name or logo on a document that will circulate. It survives forwarding and screenshotting, so the origin stays attached to the content even when the covering message is long gone.
Marking the recipient
Stamping each copy with the name of the person it went to. It does not prevent sharing, and it makes a leaked copy traceable, which changes behaviour more effectively than any restriction.
Image watermarks
A logo works the same way as text and has one additional requirement: transparency. An image with a white background paints a white rectangle across the page, obscuring the content behind it.
Use PNG, which supports transparency properly, and confirm that the background is genuinely transparent rather than white. Keep the image large enough to be legible at the opacity you are using, since a small logo at fifteen percent opacity is effectively invisible.
Removing a watermark
Worth understanding both because you may need to and because it clarifies what watermarking is worth.
If the watermark is a discrete object on the page, an editor can usually select and delete it. If it has been merged into the page content, removal means editing page content, which is more work and entirely possible. Either way, a determined person gets there in minutes.
Watermark a PDF in your browser
Text or a logo, at any angle, colour and opacity. The file never leaves your device.
Common questions
Using them for what they are good at.
01Does a watermark protect my document?
No. It is ordinary page content and anyone with an editor can remove it. Watermarks communicate status to people reading in good faith, which is genuinely useful, but they are not a security measure.
02What opacity should I use?
Between ten and twenty percent. That is clearly legible as a mark while leaving the document comfortably readable. Above thirty percent it starts competing with the text.
03Should the watermark go behind or in front of the text?
Behind, where the tool offers the choice. It keeps the text fully crisp and puts the mark in the background. In front works and slightly softens whatever it overlaps, which is noticeable on dense pages.
04Can I watermark only some pages?
Usually yes. Most tools accept a page range, which is useful for marking an appendix as confidential while leaving a cover page clean, or for stamping only the pages that will circulate.
05My logo has a white box around it. Why?
The image has an opaque background. Use a PNG with genuine transparency rather than a JPEG, which cannot store transparency at all and always fills its background with a solid colour.
06Can watermarks be removed?
Yes, by anyone with a PDF editor, usually in a couple of minutes. That is inherent to what a watermark is. If content genuinely must not be seen, removing it from the document is the answer rather than covering it.