Hi Jeffrey,
The border collapse property sets whether a table border should be collapsed into a single border or detached. You can achieve this by specifying CellSpacing property as zero. Please refer the following code snippet to achieve this:
[c#]
//Similar to css's border-collapse property
table.Properties.CellSpacing = 0;
Here is the sample for your reference:
http://websamples.syncfusion.com/samples/XlsIO.Windows/F62751/main.htmKindly take a look at the sample above and let me know if you have any other questions.
Thanks,
Melba