When it comes to the finishing the edges, there’s a few different options. Most of the bought kits come with a few bits of sandpaper just to get you started. These should ideally be the stronger backed type .eg. fabric to protect your fingers a bit better and last hopefully a little longer. I found the thin strip types were quite useful as you could form it around your index finger, and arris the edge quite effectively will little risk of straying onto the glass surface itself, avoiding scratches when finished. I’ve also tried an electric sander, which was very effective too in flattening off the worst of the ‘craters’ in the break. Kept relatively flat, the sander does a lot of the work for you, though you need to avoid turning the bottle edge into the paper too much, which very quickly cuts though the sandpaper. Used as it’s intended (flat to the surface) , it’s a labour saver and quite neat in finish and uniformity as you vary the grit used.
With the bought kits, you sometimes also get a small portion of pumice powder, which you sprinkle onto a flat glass surface, and mix into a paste with water. The bottle edge can be rotated onto this surface (like a Ouija board action), and this slowly smoothes up the edges. It’s quite a slow and messy process, and leaves you with a residue that you wipe/rinse to check progress, and also need to store or dispose of afterwards. It’s much less effective in terms of effort than the final method I chose.
Having seen diamond pads in action for years at work, used to hand arris glass and mirrors quickly and neatly, I knew these would be my preferred tool to complete the edges of cut bottles. I purchased a range of three different grades ( black -120 grit, red – 200 grit , yellow – 400 grit), and used them all to smooth down, level off and finish up the bottle cut. They are a good size to grip, but because they are quite large for smaller bottles, it’s easy to get over-enthusiastic and slip onto the glass surface, leaving scratches that you won’t be able to polish out. This is more of a problem than the finer sandpaper slips, which I found can be polished out with a bit of jewellers Rouge and a felt bob. The odd slip is annoying, as I want the edges perfect, but on reflection, they are already far superior to the finished examples shown in the two books on bottle cutting I’ve got. They are really quite poor, and you’d be reluctant to take a sip out of some of those to be honest. Good progress made on finishing so far. I’m sure the diamond pads are the best way, and will get to the perfection (100% no scratches or shells) stage with more practise.