Modifying an open source font, where to start?

Hi everyone! 

I've got a job where I need to modify a font for the customer. The font is open-source and i have access to the .ttf files.

The thing I'm uncertain about is where to start the whole process. For the first sketch I gave them i just opened the .ttf file in Glyphs and converted it to a UFO, and from there i made the necessary modifications. 

If their client likes the font I'm doing I will have to work with two masters, a regular and a bold, and then interpolate some weights in between. 

But my gut feelings tells me this might be the wrong way to approach this job, maybe it's better to create a fresh UFO and then copy the kerning and glyphs to it, so that i get a clean file?

Has anyone else done a similar thing like this and would like to share the process so I can get an idea of how I'm suppose to do this "the correct way". 

Any help and insight would be nice :) 


  • Georg Seifert
    I don’t see a reason why to copy everything to a new file. 

    And if you work in Glyphs and you like to interpolate, I would suggest to put both masters into the same file and set up instances. That way it is much easier to work on both masters and test the interpolations. 
  • Alexander Orn
    Ok, thank you Georg! :) 
  • Jens Kutilek
    It's highly unlikely that you will get two interpolatable masters if you just open 2 TTFs. The TrueType conversion probably didn't keep the outlines compatible.

    If you can find source files (Glyphs or UFO) for the fonts, it would be much easier. A lot of so-called "open source" fonts don't have them though, which I personally find a bit ironic ;)
  • Dave Crossland
    Dave Crossland Posts: 1,402
    If I was you, I would search Github for sources, then reach out to the original designer and see if you can get sources, and then ping me and ask me if I know anything else about them. Sadly plenty of libre fonts have original contributors (individuals or organizations) who abandoned the projects, or even passed away, and it can be a bit of a byzantine journey to figure out what's going on. 

    Are your modifications 'convergent' (such as fixing stuff where you might want to keep the old name in whole or in part) or 'divergent" (as in, changing the design into something else that goes by another name)? 

    What license is that project under?