You can increase their thickness. Go to Document Options: Lines and Curves.

I tried that but it makes them really thick. I can't seem to find a setting that would just thicken them slightly. Any suggestions?

… I tried that but it makes them really thick …

What is chosen as Measurement Units? - Inches?

It might be easier with small Measurement Units.

Try e. g. Points, or EVPUs.

FYI:

1pt = 4e

Try e. g. a staff-line thickness of 0.5pt (= 2e).

If that is too thin, try e. g. 0.75pt (= 3e).

What’s your OS and how are you printing?

Thanks, but still no luck—tried it both with points and EVPUs. No matter what I do it's either too thick or no change at all. I am not even to the printing stage yet. I need to make the staff lines thicker and then reduce the exported PDF to fit in a program booklet. In the past I've run the PDF through Photoshop and added a stroke to the staff lines but that is a cumbersome workaround.

I am working on a Mac Pro using OS Sierra, Finale version 25.5. I print to a Canon multifunction printer.

>I am working on a Mac Pro using OS Sierra, Finale version 25.5. I print to a Canon multifunction printer.<

Ok, that doesn't tell us how you're printing nor anything about the printer but it's a start. Let's see if this helps:

On a Mac, the only way to get true black is to go to the Tools menu and select Graphics — this will now add the Graphics menu to the toolbar. From Graphics, select Export Pages... chose PDF from the drop down menu. Pay attention to where it saves this file. Now open this pdf and print.

Note: selecting pdf from the Print menu will not generate true black on a Mac in Finale 25 or 26. Only Graphics/Export... does. Windows does not behave this way.

Let us know what happens and what Canon printer you are using.

Thanks, Mike! I didn't know that I wouldn't get a true black without using the process you suggested. It works well enough now.

Printer is a Canon IR ADV C7055/7065 PS

This is not the only laser printer that doesn't like Finale 25/26 on the Mac. There are certain Brother and HP lasers that are worse. The Graphics/Export... menu is the only thing that allows them to work.

Apple and Canon don't have the cosiest relationship when it comes to drivers and it's possible that yours are out of date. Not sure when this printer was made other than between 2007–2013. My suggestions include contacting your vendor to see if an updated Mac driver is available. If you were using its PostScript functions, probably time to get away from that, too — at least where Finale is concerned.

Some of my school clients have old Canon printers that stopped working properly when Mavericks and Yosemite were released. Apple no longer included the drivers in the OS for those but I found other drivers that did the job at canon.jp.

Thanks again Mike. I'll have someone check that printer driver. I'm not really good with the tech side of things.

A printer like that normally has a maintenance contract. Let that company earn their money, right?

"Note: selecting pdf from the Print menu will not generate true black on a Mac in Finale 25 or 26. Only Graphics/Export... does. Windows does not behave this way."

This is true even on Finale 27.0.0.782, MacBook Pro running Big Sur. Do we know if there is a fix coming for this at any point?

We do not know.

>this is true even on Finale 27.0.0.782, MacBook Pro running Big Sur. Do we know if there is a fix coming for this at any point?<

According to MM and at least one person who has tested, that is not true anymore. When I took a quick look, it appeared to me that is correct. I'll see if I can find that thread.

We both noticed that the change didn't happen till after a shut down and reboot. So try that first and see if you notice a difference. If not, use the Submit a Request link at the top of the page.

With Catalina, I've noticed that a normal reboot does not allow certain VIs and plug-ins to load properly. One needs to shut down completely then boot. Others have noticed this with Big Sur. It's inconsistent. With the latest Native Instrument updates, most loaded fine after Native Access ran the installation, a few needed a reboot but Kontakt 6.6 didn't load till I shut down first. There have been others.