Automatically Watermarking Word, Excel, PowerPoint and PDF files

Clavin Fernandes

Clavin Fernandes

The Muhimbi PDF Converter has, for many years, offered the ability to automatically add a wide variety of watermarks to PDF files. Watermarks can be added from SharePoint Online, SharePoint On-Premise, Power Automate, or our API.  Beyond that, the watermarks themselves can be of many different types- text, images, QR codes, Barcodes, you name it. This works amazingly well, but up until now has always been limited to PDF files.

Now, after our development team has released  the results of all their hard work, we're very pleased to announce that watermarking is now available for MS-Word, PowerPoint, and Excel files in addition to PDF files.

As they say on TV, " But wait- there's more!"  This new watermarking ability doesn't only bring our existing watermarking  functionality to non-PDF files, it does so without having to learn a new way of adding watermarks.  Watermarking an Office file works EXACTLY the same as watermarking a PDF file.  It uses the same coordinate system (Points, 1/72nd of an inch), everything works as expected.  Naturally, there are some minor limitations inherent to the various file formats, see the end of this post for an overview of things to be aware of.

Watermarking goes hand-in-hand with applying security, mainly to prevent documents and watermarks from being easily modified. We have extended our file security facility to MS-Word, Excel and PowerPoint as well. For details see this blog post.

This new functionality is available with immediate effect in our SharePoint Online, Power Automate and REST API. There is nothing to do or install, it is available automatically to all new and existing users.

The On-Premises version of the Muhimbi PDF Converter for SharePoint and the Muhimbi PDF Converter Serever Platform, include this new technology starting with version 10.1, which is available right now.

Common uses cases for applying digital watermarks to documents are:

  • Displaying the document status in the document (e.g. Draft, Final, Confidential, Embargoed)
  • Adding user specific info when the document is opened (e.g. ' Opened by John Miller on 13/7/2020 from IP')
  • Preventing piracy and unauthorised use, protect intellectual property.
  • Auditing and tracking.
  • Add labels for compliance and corporate policies.
  • Displaying metadata associated with the SharePoint item, or other external data sources ( Author, Project name, Due date)
  • Adding template content to all documents, e.g. legal disclaimers or copyright messages.
  • Automatically applying corporate branding such as the company name and logo.
  • Embedding important - machine readable - data using barcodes or QR Codes.

A video explaining some of these concepts can be found in our Knowledge Base. An overview of all watermarking related articles can be found here.

WM On Open - Word vs PDF vs Excel vs PowerPointA simple 'Confidential' watermark applied to MS-Word, Excel, PowerPoint and PDF.

Watermarking of files works through all layers of our solutions and services including SharePoint Designer Workflows, Workflow Manager, Nintex Workflow, K2, Visual Studio Workflows, UiPath, Power Automate, Power Apps, Azure Logic Apps, our SOAP API, the Online REST API and even the SharePoint User Interface for both SharePoint On-Premise (SP2007-2019) and SharePoint Online.

SharePoint Designer Workflows

For example, adding barcodes to Word, Excel, PowerPoint and PDF is now easy to achieve via SharePoint Designer workflows. We support most common barcode types including Codabar, Code11, Code32, Code39, Code39Extended, Code128, Code128A, Code128B, Code128C, GS1Code128, Code93 and Code93Extended.

Although there are many good reasons to automatically add barcodes to documents, the use case we see over and over again is document management. At some stage documents will make their way outside of the document management system they are created and stored in. How do you figure out important details for such documents? Barcodes can play an important role in this.

Nintex Workflow

Nintex workflow is particularly popular with our on-premise SharePoint users (SP2007-SP2019). A super friendly and powerful product to create and visualise even the most complex workflows. All watermark types supported by our core engine are available in Nintex Workflow as well.

In the screenshot below you can see our Nintex 'Text watermark' action. It is very flexible and provides full control over dynamic content, formatting, positioning, rotation, word wrapping and much, much more.

Nintex Watermark

Power Automate, Power Apps and Logic Apps

The fastest growing workflow platform in the world is Microsoft Power Automate (and by extension Power Apps and Logic Apps). We provide extensive support for this platform by exposing all features provided by our core engine including Document Conversion, File Security, PDF Merging, OCR and naturally watermarking.

Fox example, use the Image watermark action displayed below to automatically add a background image, or header image, to all your MS-Word, Excel, PowerPoint and PDF files. Easy, fast and powerful. Have a look at the various Power Automate tutorials available in our Knowledge Base.

Power Automate Watermark

Real-time Watermarking

One of the most powerful watermarking features provided by Muhimbi's range of software and services is the ability to apply watermarks in real-time when documents are opened. Think about it, the files in SharePoint are neutral without any watermarks. However, the moment they are opened by users, our software makes sure that custom watermarks are applied while the files are in transit to the user. As a result every user gets their own personal watermarks.

There are many use cases, but the most common use case we see is what we call 'DRM Light'. User details such as full name, user id, ip-address and time stamp are embedded in the document, either visibly or hidden. If a document then shows up in a place where it is not supposed to (e.g. in a data leak) then you know exactly who to reach out to and have a bit of a difficult conversation with.

For more details see the blog posts about this technologies for SharePoint on-premise, and SharePoint Online. The screenshot below illustrates how this can be enabled for the different document types.

WM On Open - SP2016

If real-time processing is of interest, especially in combination with SharePoint Online, then please familiarise yourself with Watermark & Secure 'OnOpen' in SharePoint Online - FAQ.


Different file formats all have their own peculiarities so it is important to be aware of the limitations and potential issues that may arise.

PDF is the ideal format when it comes to watermarking as anything is possible. You can place content anywhere on a page with pixel perfect precision, and each individual page can be targeted exactly. Unfortunately, that is not the case for all file formats, particularly MS-Word, which describes text and formatting in the docx file, but it is up to the editor - in this case MS-Word - to render that information to the screen or 'paper'.

  1. Modern Office formats only: Watermarking is only supported in modern Office formats (DOCX, XLSX, PPTX), legacy formats (DOC, XLS, PPT) are not supported. If this is a problem then use the Muhimbi PDF Converter's other facilities to convert old style documents to their modern equivalents.

  2. Layering / z-order: This is true for PDF as well, but make sure you don't hide your watermarks BEHIND your document's content. For example placing your watermark in the background of a non-transparent document such as a scan, will hide the watermark. Note that for Excel and MS-Word, watermarks are ALWAYS located behind the document's main content.

  3. Targeting individual pages: PDF and PowerPoint files allow individual pages to be targeted, for example only add the watermark on the 3rd or last page. Unfortunately this is not possible with MS-Word and Excel. In MS-Word watermarks are applied to an entire section, it is not possible to target a watermark to a specific page unless that page has its own section. In Excel it is not possible to target individual pages either, all pages in a worksheet automatically get the same watermark. It is possible to apply different watermarks to different sheets in the workbook though. If configured accordingly in Excel and Word, the first page can have a different watermark compared to other pages.

  4. Mandatory MS-Word Headers: Watermarks are added in MS-Word via page headers, that is just the way that file format works internally. When applying watermarks to Word files it is therefore essential that the headers have not been removed from sections. Our software cannot add watermarks to sections without headers.

  5. Real-time watermarking in SP on-premise: The interaction between MS-Office and different SharePoint on-premise versions is extremely complex. To keep things manageable our software disables co-authoring (multiple people editing the same document at the same time) on libraries that have real-time watermarking enabled and where our 'Apply when editing' setting is enabled.

    Due to the way Office files are fetched, for the more modern SharePoint versions it is recommended to enable the 'Apply when editing' setting to make sure watermarks are consistently applied. This only applies to real-time watermarking, applying watermarks via workflows does not suffer from this limitation.

  6. Office Web Apps: When using real-time watermarking and Internet Explorer is used in combination with Office Web Apps, we recommend setting the 'Default open behaviour' to 'Open in the client application' and not to 'Open in the Browser' ('Advanced Library' settings for the relevant Lists and Libraries).

  7. Real-time watermarking on read-only files recommendation: It is important to put some serious thought in how your documents will be used. For example let's say automatic watermarking is enabled every time a document is opened. A user opens the document for editing purposes (which applies a watermark automatically), the document is then saved including the new watermark. When the document is then opened again a watermark is applied again.... and again.... and again. It is for this reason that we recommend using either a filter to only apply real-time watermarks for certain situations, or to only enabled real-time watermarking on read-only documents or folders specially created and maintained for sharing these watermarked documents.

  8. RTF Watermarks in PowerPoint: We support many watermark types including one that allows rich text to be inserted via RTF. Unfortunately RTF is ignored in PowerPoint, it only displays the textual content embedded in the RTF without formatting.

  9. Excel watermarks require one free header / footer slot without image: In Excel, watermarks are added via headers and footers. Excel has 6 slots, 3 in the header and 3 in the footer. Muhimbi's software requires at least 1 slot to have no image present or it will not be able to apply the watermark.

This new functionality is very powerful and in some cases complex. Any questions? Leave a comment below or drop us a line, we love to help.

Labels: Articles, Excel, Flow, News, Nintex, pdf, SharePoint Online, SP2010, SP2013, SP2016, SP2019, Watermarking, Workflow


Clavin Fernandes

Clavin Fernandes

Developer Relations and Support Services @ PSPDFKit

Clavin Fernandes is a Microsoft Business Applications MVP and works in Developer Relations and Support Services for PSPDFKit.

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