Is there are way to find unwanted cell borders or different thickness of borders in Calc?

We are experiencing a lot of problems with some of the Calc document we use. There’s no visual difference between some border line thicknesses when editing, but when exporting to pdf we get some real ugly line differences. These differences originate from any modifications we did to adjactant cells, or just a part of a certain border etc… This is a painstaking work to correct as we have to guess the cells that are responsible for this.

Is there no easy way to visualise any potential problems before exporting to pdf?

The problem is obviously due to a way of using direct (hard) formatting which should be considered a misuse. As soon as you shift to formatting done exclusively using named cell styles the problem will vanish.

To transform sheets with lots of hard cell formats into style-formatted sheets you need first to specify and to actually define the wanted styles in a purposeful hierarchy. Then you need to apply these styles to the respective cell ranges based on the visual judgement and/or on specified rules. Finally you need to clear direct formatting (Ctrl+M) for the respective ranges. Please note that LibO also will clear ConditionalFormatting for these ranges then. You need to preserve and reinstate it if wanted.

Don’t miss to define your style hierarchies first in the templates you use, especially those for future use. Already existing documents based on these templates will import the new styles when opened next time if you ‘Yes’ the respective prompt.

If you want to get some automatized help with your task you will need “introspective functions” returning values for cell attributes. There are no standard functions for the purpose. “Macro” functions of the kind you can find here e.g. A transitional step making the formerly invisible differences eye-catching can be CF based on introspective functions.

Concerning cells with text content where pieces of the text are formatted differently, the above does not apply.

Thanks a lot for the detailed answer! In this case, hard formatting was needed, but I’ll see if I can rework it with cell styles.

You are welcome.
One additional remark: If your problem is restricted do border-line widths and the area you have to check is well limited, you will see small differences at a higher zoom factor. On my standard screen (1920 x 1080) e.g. I can see the difference between 0.5 pt and 0.75 pt horizontally and vertically as well with zoom = 150% or higher in ‘Normal’ view.

The physical resolution of such a screen is only about 40 pix/cm (“100 pix per inch”). Reduced with regard to the 160% zoom this is about 60 “ppi” in paper measures. Printers have 300 “dpi” or more and can show smaller differences.