Thread: Honing on glass

I spilled the beans in another thread, so I'm going to say more here.

I started one day thinking about finer and finer honing, chrome oxide, diamonds, etc., and remembered those old hones that double-edge people used to swear by in the days of carbon steel blades: concave glass and drinking glasses. I think we've all read the stories about keeping a DE carbon blade going for months by honing (burnishing? stropping?) in a drinking glass, so I started wondering how it would work on a carbon steel straight. I took a freshly honed straight (12k Naniwa, then chrome) that hadn't been stropped and a piece of glass and treated the glass just like an infinite-grit hone: some water, then some gentle rubbing as with a normal hone, followed up by more rubbing on the dry glass.

I thought the difference was pretty amazing. I think what it was doing was a harsher version of what the strop does: aligning, and perhaps burnishing, the edge, not cutting on it, and it seems to do an amazing job of that. My straight worked a lot better, and when I tried it on my violin making knives, which I have more experience with, the improvement was substantial. I posted it on a violin board, and to some friends, and they're reporting back that it works great on their knives. While I felt like my straights were just a bit short of a fresh DE blade, now they've approached that a lot closer, and I really like the way they're working.

When you think about it, if it worked well on carbon DE blades, there's no reason it wouldn't work well on straights.

Razor maker extradonaire Robert Williams began using diamond spray on a spyderco ultrafine and got great results. Your experiment brings that to mind. I would probably try some chrom-ox or diamond spray on the glass just to see if it gilds the lilly.

My Grandad said they used to run a razor blade around the inside of a glass during the war to put an edge on it as they didnt get to replace them very often

I started this line of thought by using chrome on glass, as a matter of fact, on my first razor. I had the chrome in my violin shop, but no strop. So I used glass as a backing for the chrome, and that's still what I do. I do the bare glass after the chrome, however, and it's an improvement.

There are a few threads on here about trying Glass Hones and Strops, if you use the Advanced search function you should be able to find them , most started from the exact same thought process as you had.. Somebody will post a question about the old DE sharpeners being glass, and then somebody tries it on a SR...

Some people swear by using CBN and other Sub-Micron polishing agents on Stones, Ceramics and Glass plate

I did quite a few searches here and via google and didn't find much, except regarding DE blades. Maybe you can point me to something.

The last guy I remember messing with it went by "Gibbs" you might start by searching his old posts, if you hit the search function then go to the "Advanced Search Function" you will find a ton of info hiding in the dusty archives of SRP

Originally Posted by mdarnton

I started this line of thought by using chrome on glass, as a matter of fact, on my first razor. I had the chrome in my violin shop, but no strop. So I used glass as a backing for the chrome, and that's still what I do. I do the bare glass after the chrome, however, and it's an improvement.

I have tinkered with this as well.

Fine near micron grit on glass works quite well. Rinse the glass to
finish the process. One source of grit is slurry from another hone.
Sprays of diamond or CBN work fine

The problem I found is that to some extent it is possible for me
to get the razor too sharp for a comfortable shave. Some call the
too sharp edge a harsh shave but it will often calm down after a shave or
two.

Another problem is the progression of grit as you approach
the need for honing on glass. Like all other hones the
progression has no short cuts. Near micron bits are gosh
awful fine and demand the edge be ready for a grit
that fine.

Loose grit and slurry works wonders. Large and small stone is often sliced with
a wire saw where the "blade" has no grit but grit is carried by
the wire. Diamond/ gem cutters use oak and copper metal that grabs the suspended
grit (slurry of diamond in oil) and drags the grit across the gem.

I haven't tried that, but I do know from experience that you can get a serviceable, if not ultra-fine, edge on a knife (NOT a razor, obviously!) by honing on the bottom, unglazed rim of a coffee mug. I've got one mug in particular that works great for this.

Originally Posted by niftyshaving

Loose grit and slurry works wonders. Large and small stone is often sliced with
a wire saw where the "blade" has no grit but grit is carried by
the wire. Diamond/ gem cutters use oak and copper metal that grabs the suspended
grit (slurry of diamond in oil) and drags the grit across the gem.

I've only read that in "De diversis artibus" by Theophilus Presbyter written in 1100, have you got some more up to date info on it?