Add watermark

A draft sent for comment has a way of coming back months later as if it were final. A sample chapter goes to a prospective client. An internal copy is shared with a partner and you would like to know where it came from if it turns up elsewhere. A word across each page settles all three.

Set the text, then the opacity, angle and size. Around a quarter opacity is the useful range: clearly visible, still readable underneath. Anything other than plain Latin characters pulls in a font subset of about a megabyte and a half on the first run, so Korean works but takes a moment. Japanese, Chinese, Cyrillic, Arabic and other scripts are not in that font, so a watermark containing them is drawn with the fonts on your device and placed as a transparent picture: it cannot be selected or found by text search, and its exact letterforms depend on the device. One line is drawn across the middle of every page, with no page range and no tiling.

This is not protection. The mark is ordinary text sitting on top of the page, and anyone with a PDF editor can select it and delete it in seconds. Use it to label, not to secure. If the file must not be opened at all by the wrong person, Protect sets an open password instead.