I did some graphite edges again, this time going for a mirror finish (I'm still not sure they couldn't be even more shiny).
(The 2 pictures above show the difference between the graphite edge on a trimmed but otherwise untreated edge and a trimmed and sanded edge with burnished graphite.)
When doing all 3 edges, I always start with the front edge because that's the most difficult one to do without making too much of a mess when it's curved from rounding the book.
My process is first of all sanding (so much sanding in bookbinding).
I started out sanding with a 120 grit and worked my way up to 400 before applying a graphite-paste layer. There are pre-made liquids for graphite edges, but I mix my own batch each time, because graphite powder is what I have, so I use that and it's not really difficult to mix it with a thin paste.
It looks pretty patchy before polishing, which is perfectly normal.
When applying the graphite paste the edges should be dust and fuzz free to avoid weird specks on the finished edge. The issue with those specks is that they are usually thicker than the rest and tend to flake off.
Next is waiting for the graphite-paste to dry a bit and then start polishing with a wad of cotton or any soft fuzz-free cloth until the edge is shiny and no graphite comes off anymore.
My graphite paste was a tad too thin though. I polished it, but noticed after a bit I wasn't getting a good coverage on the edge. So I just added another layer, let it dry again and polished some more.
This time I really wanted to see if I could get a mirror finish by burnishing the edge with an agate burnisher. If you do this, make sure your tool, agate burnisher, bonefolder or whatever you use, is clean and unmarred. it's terribly annoying to get scratches on the edge at the very last step.
I finished up with a thin layer or wax to protect the paste from getting reactivated, polished and burnished again with cloth and agate.
I'm not sure that's the best it can be, but it certainly is more shiny than the merely cloth polished edge.
