The Add Watermark tool only accepts a rotation value of -45, 0, 45, or 90 degrees; any other value is rejected.
Adobe Acrobat's watermark rotation setting offers -45, none, 45, or a custom angle, and the 45-degree diagonal is the standard choice since it is harder to crop or edit out. Add watermarks to PDFs - Adobe Acrobat
Add WatermarkDiagonal Watermark PDF Angle
The Add Watermark page defaults the rotation selector to 45 degrees, the diagonal option, before the user changes it.
Select the 45-degree option from the rotation dropdown.
Add the PDF you want tilted before choosing a rotation value.
Checking Diagonal Watermark Placement
Review the preview to confirm the text sits at the chosen angle.
Adjust the opacity slider to reduce the visual weight of the mark.
Continue with Adjusting Watermark Opacity or Applying Watermarks to Every Page.
Frequently Asked Questions about Diagonal Watermark PDF Angle Options
How do I set the watermark to a diagonal angle?
Choose the 45-degree value in the rotation menu.
Where do I find the rotation options?
Open the rotation selector on the Add Watermark page.
How do I apply the watermark to the document?
Click the apply button after setting the angle.
Where do I download the finished file?
Download the updated PDF from the results screen.