A family of Microsoft word processing software products for creating web, email, and print documents.
Why everyone continues to suggest creating a PDF in order to resolve the issue doesn't make much sense - You've already stated that you've done that :-) Apparently nobody seems to understand that the problem is occurring in PDFs as well as hard copy... and if the lines are generated in the PDF, they will show up regardless of which program the PDF is printed from.
Most printers [PDF is a print process] 'see' the cell walls & interpret the use of no color as white (i.e., apply no ink here). That often results in the faint hairline issue you're experiencing. The solution is to make the cells blend together so the printer sees them as one large area of a specific color.
The issue is rather common, though, & there are at least 2 ways to resolve it.
- Select the left column, then use the Merge button on the Table Layout tab of the Ribbon (IMO, this is the preferable solution)
- Select the left column, then apply cell Borders which are the same color as the Fill.