R E K on Nostr: I only need to turn the grey tones into either black or white, so I just keep a ...

I only need to turn the grey tones into either black or white, so I just keep a version with greys as an underlay reference(as you said), duplicate the layer and remove all greys by playing with levels. Then I just add some black pixels back in, as needed. Sometimes I have to alter the design slightly so that it reads better (the grey permitted for a greater concentration of information without it looking like an incomprehensible mess).