◈ Watermark PDF

Adding a watermark stamps text or a mark across your pages, which helps label documents as Draft, Confidential, or your own, and discourages unauthorized reuse.

What adding a watermark does

A watermark overlays your chosen text on every page at an opacity and angle you control, so it is visible but does not obscure the content. It becomes part of the saved PDF, traveling with the file wherever it goes.

Because the mark is drawn onto each page rather than shown only in a viewer, it prints and displays for everyone who opens the document and cannot be toggled off. Controlling the opacity lets you keep the underlying text readable while still making the label unmistakable, and a diagonal placement is harder to crop away than a small corner stamp. Applying the watermark as the last step ensures every page of the finished document is covered.

When to watermark a PDF

• You are sharing a draft and want it clearly marked as not final.
• A document is confidential and should be labeled as such.
• You want to brand proposals or reports with your name or company.
• You are distributing samples and want to deter copying.

How Slate applies watermarks locally

You type your watermark text and set its look, and Slate draws it onto each page and saves a new PDF on your device. Because the process is local, confidential files are never uploaded. The original remains unmarked so you always keep a clean copy.

Tips for an effective watermark

• Use a moderate opacity so the mark is clear but the text underneath stays readable.
• A diagonal angle is harder to crop out than a horizontal one.
• Keep the wording short, such as CONFIDENTIAL or your domain name.
• Apply the watermark last, after merging and organizing, so every final page is covered.