Always be careful on so called shave ready razors, I always assume they are not shave ready.

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True! However, the person that I bought it from had a small side business with his dad on restoring and selling vintage razors. His dad passed away and the seller was left with a boatload of razors. He is selling them because his memories of working with his dad was too much to bear. At the nominal price I paid, the razor is indeed shave ready or I have my first razor that I can learn how to hone without worrying about destroying an expensive razor. Either way, I see it as a win-win.

First, I am by no means an authority on this topic.

I watched his video where 2 tiles were lapped against each other with an abrasive between. Rotating one tile 22.5 degrees between cycles until both tiles were concave against a straight edge. This tiles become the lapping plate.

It was explained that the folks at Dovo specified a convex stone as their preferred method.

Here is the link to the last video on it.



Jarrod will supply Belgian coticles lapped convex.

I believe the reason is to compensate for the variances that sometimes show up in the trueness of razors.

I have razors honed 'very well' from 5 sources. I gotta give a wee bit of favor to his result, but I do not think I will pursue it for my own practice.

As Keith pointed out, I'm sure Jarrod will be stopping by.

And three seconds to spare.

hello ya'll, on the convex stone issue...in Solingen since prior WWI, master grinders train as a guild using a principle that a razor's edge is always further refined (ie post 'bevel setting') with a stone made convex by hand. They 'stole' this from Sheffield, England, I was told (thru translation) by a very senior fellow the first time I went there 8yrs ago - so there are likely late Victorian era Sheffield blades which adhered to this notion when produced. The old hand also told me when he was a pup he'd worked under an old grinder who trained a famous USA cutler and they did the same thing over there. I know from speaking with someone at Theirs-Issard that they know of it, too. Within the industry it is no secret, but in our modern e-culture I'm the only one carrying this silly torch.

You can see the basic concept below;



Part of the Solingen master grinder's apprenticeship is proving mastery of tools needed for work. In so doing, the masters will give an apprentice a very large flat typical JP-produced alum-oxide-based splash-and-go style waterstone perhaps of 10x4x1" (nobody uses small hones there from what I've seen!). They demand the apprentice 'bring this back to us when you have made it have X% gradient along the long axis and Y% along the short axis, and here are the items you can use'. The apprentice can use files, sandpapers, straight edge ruler, feeler gauges, depth micrometer, caliper, some nagura/slurry stones, and ~blunt thick knives. Like long division, they must prove to prepare this by hand without automated tools. The apprentice first takes the file to the long axis 'rails' of the bench stone and brings those down so that once reduced they'd be correspondent to the Y% gradient demanded along the short axis, and then begins dutifully blending that drop off with the midline summit via the sandpaper/knife/nagura over some days...when that's finished, they'll repeat the process to the two short 'rails' of the bench stone at either end (reduced to a correspondingly different gradient, as the Germans feel the ellipse shape offers the most control to the honer). Finally they measure with the various tools to see that the shape corresponds to the ellipse desired.

The German master grinders I've spoken to believe there's no such thing as a truly flat razor once it leaves the process of using the wheels pictured below - there is only not enough magnification used to observe the small deviation from straight perfection.


So as the double hollow grinding wheel thing necessarily makes tiny deviations from straight, they aim to have the curve of the whetstone exceed the allowed curve of the razor. In theory, every razor is put flush against a straight reference and a bright light used to observe how much if any deviance from straight is presently visible to the naked eye. As long as the bench stone has a curve slightly more intense than razor's warp, it would not matter if the razor's curved with the bottom of the curve facing to the stone or facing to the ceiling as one honed; in both cases, the stone will only touch the cutting edge along one continuous contact patch, and as you move along the stone in a broad elliptical pattern of motion you'll ensure that the entirety of the cutting edge touches some stone with each lap.

With a stone that's dead flat and a razor that's within tolerance but its curve facing the ceiling, you're unable to have one continuous contact patch during each stroke if you position your blade's spine-to-grind-line near plane flush to the stone's (true) plane - instead, you will either wear away at the intermittent points of the edge which are making contact while ignoring the part that is not, or you do the so-called "rolling-X" stroke (which means that your razor's spine-to-grind-line plane and the stone's plane are NOT being held parallel to one another).

In the instances this topic's come up you will in this hobby routinely read people who retort to this that using a narrow stone, a cylindrical rod stone, or just an edge of their incumbent stone is the same concept; I would anticipate that here. That is simply folly for fools. An ellipse, sphere, and cylinder are different shapes. With the convex stone method, you are grinding at the cutting edge with an angle of incidence of blade to stone that is otherwise impossible on all other methods described. It doesn't matter if you're employing the "rolling-X" on a flat stone, or using the very excellent Spyderco cylindrical rods to hone, a honing on an imaginary corner of your big flat bench stone, etc....in any of these methods you CANNOT reduce the angle of the bevel plane to that which would be below (= more acute) what is produced by an entirely flat stone. The reduction of the cutting angle is one of the reasons they do this.

The Germans espouse the use of the convex stone for specific benefits, which are in order of importance to them 1) guaranteeing all of the cutting edge touches the stone on every honing lap, 2) reduces wear on the razor, 3) reduces the cutting angle of the bevel plane.

In the case of the stones that I routinely use now, the reduction of the bevel plane cutting angle vs flat stone is -0.183°, which is not a completely trivial consideration when you consider the range of a Western straight razor's bevel plane and the standard deviation thereto. All things being equal, I'd take a slightly sharper bevel triangle than a slightly more obtuse one (which is what we get when we hone with tape) every time. After all, that is a big factor in what we refer to as keenness, and the reason why the harsh-but-acute DE blade feels so sharp vs a 'real' straight. In my view we only hone with tape to solve problems that the convex stone was designed to fix.

I was able to create a uniform spherial stone shape by using the old method shown at for producing Newtonian telescope mirrors. Rubbing two pieces of granite stone together as in the Indian instructional on Newtonian mirrors, I ended up with what u can see here = a "lapping plate" that forces a perfectly spherical shape to the bench stone. Granite being so darn hard, I doubt that this lapping plate will need service for the rest of my retailing career. Its production was, I assure ya'll, no picnic. Certainly harder than grinding glass! I routinely check my stones' shape with the straight edge, use a slurry stone in concentric circles most intense at the least used parts of the stone, and reshape the stones as needed with the special plate (a very rare occurrence with Arkansas stones, but it does happen, and in my first Solingen trip the old grinder said they preferred Arks to all stones but just gave up on them because they can't source in the size/quality they demand and [honing many thousands of sessions per annum] will consume any stone in their job).

Once I had this sphere shaped stone I had to show it to Dovo. They fiddled with a ruler and feeler a bit, and asked how I was created it. I showed them and explained the spherical grinding method. Then asked to see me hone on the stone, which I did. Finally they said I could officially hone for them, and to remember that my sphere was an improvement, but still not an ellipse's equal. They had, for over 8yrs, previously refused to allow any 'official' decree of servicing their product.

A sphere still reduces the cutting edge's bevel plane, just like an ellipse. But it cannot solve problems of problematic razors with bad variances in their wear etc. - for that you still need an ellipse. An ellipse has the enormous advantage in that any variance of your edge line in relation to the pass along your stone can make the curve of the stone become more or less intense in its effects on the blade. Making an ellipse stone by hand is as difficult as the chortling German engineers made it seem when I'd asked how they do it ("well...it is very difficult" was their actual reply), so at this time I only have one such rock, which I show below (one can sort of see the elliptical nature).



If you're well experienced as a honer, using the ellipse the first time is like trying to ride a bicycle facing the wrong way - it feels extremely different, enough that when you're trying to set a bevel on a worn toe/heel or impart more bevel plane depth to a razor with a high variance you can easily sense what and where you're making contact. You're also potentially greatly reducing your blade/stone contact patch (this depends how you approach the stone with the blade0, which makes any pressure you impart work quickly, so it is a fast edge reshaper and only used when necessary. With the sphere, it doesn't matter how I move the blade, it is like I'm honing on the outside of a gigantic basketball, it is all the same. I would love to have a giant and formerly very common completely homogeneous surface 'La Grise' stone (as the Belgians were mining from ~2010-2014 or so at their old digs) to try my hand at hand forming again, because this is the perfect rock consistency to make this way in my view, but sadly they're no longer common (at least not in the size/uniformity/plainness I'd wish).

I don't believe in magic razor, hones, or honing contests. But I've been using Arkansas and Belgian coticule stones with a spherical shape a good while now, and I find their edge tremendous; perhaps no better than what was in a double blind, but I always want to honor/respect the Master Grinders for the difficulty of their guild's certification, and that's a big reason why I use these stones. I saw over time that every factory that showed me the operations was using stones that did not look flat as the trips to DE added up, and thereafter curiosity led to questions and learning. On well worn or badly warped razors it is a huge advantage. I'm an unabashed French apologist in my middle age, and have some old French razors from esteemed deceased marques. They're ALL warped, and yet they're all also tremendously concave - worth the bother, to me, because they flex so very well on the face. But honing them on a flat stone can cause alopecia

You can as the home user keep your razor's geometry as set on the convex stone by using a pasted strop, which will resharpen that shape without reshaping it. You can take your razor to a flat stone and you'll just wipe off the tiny geometric advantage with your stone in short order. If your razor's variance from flat is within the tolerances of the manufacturer's specification and yet still enough to cause the flat stone user experience problems while honing, you will experience problems while honing.

12 hours?? I think i will stick with my flat stone for now.

Nice vintage Boker. I guess the Joes' were busy bidding and winning. Enjoy your new toy!

Great info, and video's. But holy smokes, what a lengthy process. You sir, are more stubborn than I. Hats off to you.

Not mine, that was @Primotenore razor.

Thanks!
There was a woodworker in our shop who claimed they could use a 12x12x1" wood to produce an ellipse divot which you'd then line with sandpaper, I wonder if the paper would keep flush.
Bear in mind I am still honing multiple thousands of sessions in a year even with the straight razor industry's regress, so that hard labor put in to grind a little spherical dip in the granite pays off in the ways it makes honing the razors easier. It did not help tempering my temper.
The bevel-setting soft Ark I bought in the 'seconds' section for $40 from Dan's Whetstones is the finest and fastest bevel-setting-only hone I have ever used, and so far has not required reshaping in spite of me checking it all the time.

Sorry, I need the visuals to understand it!

Then just watch the video from the Indian fellow on the telescope glass, and then the '6/6' video linked.

Yes, but that is why I referenced the two Joe's. Primotenore and I are named Joe.

I still might not understand it. I need detailed graphics with start, middle and ending of the process with a layman's explanation.

When you rub two flat objects of equal hardness together with grinding powder between them and in a prescribed repetitive dance of motion, it is just like you having a machine that would grind eyeglass lenses, for example - the difference is that they can grind to any shape they want, while doing this manually you can only make a sphere. The longer you rub the more you'll reduce the radius of the spherical shape you make.

After you have a spherical divot in a piece of granite, if you put water and grinding powder on that now-divoted granite and rub a stone on it, you will cause that stone to have a surface shape which mirrors the now-spherical shape of the tile. The tile's shape is concave+sphere, so your stone's shape will become convex+sphere.

Thank you Jarrod

I am a "sniper" from waaaaayyy back.

Thank you, Joe.

Thank you for the detailed information.

I like the John & Wm Ragg I already have and I am a sucker for ivory so I finally pulled the trigger on this one. It’s on it’s way to @gssixgun as we speak. Still not sure about replacing the leather strop.



Happy shaving - Karl

Really fascinating stuff. Thank you!