Just how flat?

[Wid]

Just a thought, how flat does a hone really have to be to be effective for honing a straight razor. I lap every stone I get and some times it can be a job getting one done. I know an older barber that still hones razors on occasion with a Coticule and this thing has a dish in it that would freak any of us out.

So just how flat does a hone really need to be?

IMO we here tend to be just a tad ocd about our hones, myself included.

 

[Doc226]

I don't know for sure, but I think as long as the stone is flat parallel to the blade you are OK (short axis of hone), dishing is clearly OK as most old stones and barber hones are dished.

 

[PapaFish]

I've thought about this myself. Actually, the dishing would be kind of like us taping the edges, always keeping the edge in contact with the stone. I would guess it could be usable right up until the point that the razor's edge will stop shaving, which could be one heck of a dish!

 

[danjared]

As long as it does the job well, it probably doesn't matter.

One place where the issue of flatness comes up is if you are using a progression of stones, in which case having stones toward the beginning more dished than those towards the end might matter. (This is less important with most other kinds of knives since you'd only have the edge on the stone, not a razor's spine.) Beyond than, it seems not terribly important.

 

[hig789]

I found a badly dished coticule and I wish I tried it out before lapping it flat. I assume it would put a slight convex edge on the blade wouldn't it?

 

[Kentos]

I think lapping a stone flat just removes one variable from what could go wrong in a honing session. If you start off with a perfectly flat hone, any subsequent dishing probably would not do much harm. But honing on a stone with a mystery surface would be a challenge IMO.

 

[honed]

I've thought about this myself. Actually, the dishing would be kind of like us taping the edges, always keeping the edge in contact with the stone. I would guess it could be usable right up until the point that the razor's edge will stop shaving, which could be one heck of a dish!

This.

I think dished hones were the norm.
Naturally putting a slight convex edge on, strengthening the edge, pretty much what we today do with the use of tape.

Take a dished stone & then used a pasted hanging strop. Suddenly you can hone a big Sheffield tape with no tape.

My dad is a woodworker & all his stones a ski slopes. Same with all his friends sharpening stuff. Just the way they rolled.

He once gave me a really old Swedish sandstone hone. Badly dished of course & first thing I did was to lap it.
Man, did I get a whoppin' for "ruining so much good stone" when he saw the now flat stone

 

[superbleu]

reminds me of the time I scrubbed all the carbon off a well seasoned frying pan. You can hardly blame a 10 year old for trying to help out a bit.

 

[Domminigan]

This is kind of why I don't intend to true up my grindstone. It's got a wave to it as it rotates, but if you get the rocking motion down it sharpens whatever I put to it quite readily.

 

[paco664]

i lapped my coti the day i got it..... i think HONESTLY that we waste a lot of good stone with lapping....

i do however lap my 1k bevel setter....

 

[Gamma]

For honing razors - I think a flat stone is better than a dished one. I don't go crazy, flat-enough is fine. Most of my hones are not dead-on 100% flat according to a Starrett straight edge, but they're flat-enough. But - if I run into an issue - and not getting what I think is possible out of a stone - I'll check the surface for flatness first. If it's showing daylight under the rule I'll probably lap it again.

 

[danjared]

If I run into an issue, I check the razor's edge. That hasn't failed me yet, and I have stones with some slightly visible dishing.

 

[Seraphim]

My lapping films may lack mojo, but my precision granite plate does not.

It is documented flat to within 2 microns. And will never dish.

Chew on that, you luddite rock rubbers!

 

[Gamma]

If I run into an issue, I check the razor's edge. That hasn't failed me yet, and I have stones with some slightly visible dishing.

I've experienced a significantly better honing experience after taking out slight but noticable waves/dips/bellies on several stones.
I don't think it's a question of 'can you use a dished stone?' It's obvious that one can do so.
I see this being more like - 'is flat better than dished?' Personally - I see no advantage to using a dished stone. Or using tape for that matter.
It's not like I'm worried about wearing a hone out anytime soon, so that's not an issue.
If I only had one stone, and no way to replace it - I'd probably think long and hard before lapping it though.

 

[Kentos]

My lapping films may lack mojo, but my precision granite plate does not.

It is documented flat to within 2 microns. And will never dish.

Chew on that, you luddite rock rubbers!

Hmmm, so when you gonna get afflicted with GLPAD's? Start looking for that granite with the glittery sparkly thingies, or dumpster diving behind the solid surface company for scraps?

 

[Doc226]

My lapping films may lack mojo, but my precision granite plate does not.