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Clear out junk files and repair common Windows errorsFree Scan →Scan for outdated or missing drivers - takes under a minuteDriver Scan →In C#, you can add an Excel watermark either as a text-effect shape over worksheet cells or as a picture in the worksheet header. Use a shape for visible text such as “CONFIDENTIAL” or “DRAFT”; use a header picture for a logo or image associated with page layout and printing. The examples below use Aspose.Cells for .NET. These approaches can render differently across spreadsheet viewers, so check the workbook in the application and print or export workflow where it will be used.
Choose the right watermark approach
| Approach | Best suited to | How it is placed | What to verify |
|---|---|---|---|
| WordArt text shape | Text such as “CONFIDENTIAL” or “DRAFT” that should appear over worksheet cells | A movable text-effect shape on the worksheet | That it does not obscure important cells and looks right at the zoom levels and in the viewer your audience uses |
| Header picture | A logo or image associated with page layout or printed pages | An image assigned to a header section and displayed with the &G command |
Print preview and the target spreadsheet application; Microsoft says the watermark feature is unavailable in Excel for the web |
This comparison describes the documented API patterns, not a guarantee that every Excel-compatible application will display them identically.
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Option 1: Add a text watermark with a WordArt shape
A WordArt watermark is a worksheet shape that you can position over the grid. Aspose.Cells documents creating it with Shapes.AddTextEffect, then adjusting its fill and outline. The example below follows the vendor’s documented pattern:
Do these 3 things before closing this tab:
1Clear out junk files and repair common Windows errors2Scan for outdated or missing drivers - takes under a minute3Repair Windows errors before they cause bigger problemsusing Aspose.Cells;
using Aspose.Cells.Drawing;
using System.Drawing;
var workbook = new Workbook();
var sheet = workbook.Worksheets[0];
var watermark = sheet.Shapes.AddTextEffect(
MsoPresetTextEffect.TextEffect1,
"CONFIDENTIAL",
"Arial Black",
50,
false,
true,
18,
8,
1,
1,
130,
800);
watermark.FillFormat.ForeColor = Color.Red;
watermark.FillFormat.Transparency = 0.9;
watermark.LineFormat.IsVisible = false;
workbook.Save("watermarked.xlsx");The example uses a 50-point font and specific position, size, rotation, and scale arguments. Treat those as sample values, not universal layout settings. Adjust the text, font, coordinates, color, transparency, rotation, and scaling for the worksheet’s dimensions and content. A translucent fill and hidden outline affect appearance; they do not protect the workbook or make its contents secure.
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For the API reference and vendor example, see Aspose.Cells: Add WordArt Watermark to Worksheet. The cited documentation does not specify a package version or promise identical rendering in all spreadsheet viewers.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Option 2: Add a picture watermark in the worksheet header
Use a header picture when the watermark is a logo or another image associated with page layout. Aspose.Cells documents PageSetup.SetHeaderPicture for assigning image bytes to a header section and the &G header command for displaying the picture. In the section argument, 1 selects the center section:
using Aspose.Cells;
using System.IO;
var workbook = new Workbook("input.xlsx");
var pageSetup = workbook.Worksheets[0].PageSetup;
var imageBytes = File.ReadAllBytes("watermark.png");
pageSetup.SetHeaderPicture(1, imageBytes); // 1 is the center section
pageSetup.SetHeader(1, "&G"); // Display the header picture
workbook.Save("watermarked.xlsx");The documentation also describes SetFooterPicture for a footer image, with left, center, or right sections available. Microsoft describes inserting and formatting a picture in an Excel header as a watermark workflow, but says this feature is not available in Excel for the web. See Microsoft Support: Add a watermark in Excel and Aspose.Cells: Setting Headers and Footers.
The Tool Desk
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Quick Recap
Rank #4
Check the result before sharing
- For a text shape, confirm it is positioned over the intended cells and does not hide information readers need.
- For a header picture, inspect page layout and print preview, since the watermark is attached to the header rather than placed as a shape over worksheet cells.
- Open the saved workbook in the target viewer and verify its appearance there. The cited documentation does not establish a cross-viewer compatibility guarantee.
- If recipients use Excel for the web, do not rely on its header-picture watermark workflow; Microsoft identifies that feature as unavailable there.
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