This is probably already covered, but it just explains part of my motivation for trying this convex concept. I tried to follow an old German textbook from 1846.
In this book it clearly states that you must end with a flat stone to get the best results. Also that this convex stone concept were used by the most experienced grinders, and was seen as an advanced method to thin the bevel to make it more flexible.
To look at this method as a simple way to hone a razor is probably not the best way to get people in to this.
If you finish with less then weigh of the blade on flat stone, how can you possibly manage to control the pressure on an even smaller contact point, especially at the heel and toe.
In my opinion the bevel can be shaped on a convex stone, but needs to be finished on a flat stone to be able to get any benefit out of it.
Here is a little translation with a little interpretation:
The stone intended for sharpening razors must be hard, very fine and have a uniform and dense grain structure, because without these properties it will newer be able to produce a properly fine cutting edge. Some use two or three stones of gradually increasing grain fineness one after the other, but you can certainly use a single very fine stone, which maybe requires expenditure of more time, but always come to the goal, probably even with an advantage to the cutting edge, because you do not need to erase the damage done by the coarser stone with the fine stone.
Others go further by giving the stones following one another a different shape. In particular, the following procedure from an experienced man is very advantageous.
You should give the coarsest stone a convex/curved shape, the next one to a lesser degree. Only the third (last) stone must be completely flat.
I just think that honing on the convex stones will require even more skill which is even difficult enough on a flat stone.
In this book it clearly states that you must end with a flat stone to get the best results. Also that this convex stone concept were used by the most experienced grinders, and was seen as an advanced method to thin the bevel to make it more flexible.
To look at this method as a simple way to hone a razor is probably not the best way to get people in to this.
If you finish with less then weigh of the blade on flat stone, how can you possibly manage to control the pressure on an even smaller contact point, especially at the heel and toe.
In my opinion the bevel can be shaped on a convex stone, but needs to be finished on a flat stone to be able to get any benefit out of it.
Here is a little translation with a little interpretation:
The stone intended for sharpening razors must be hard, very fine and have a uniform and dense grain structure, because without these properties it will newer be able to produce a properly fine cutting edge. Some use two or three stones of gradually increasing grain fineness one after the other, but you can certainly use a single very fine stone, which maybe requires expenditure of more time, but always come to the goal, probably even with an advantage to the cutting edge, because you do not need to erase the damage done by the coarser stone with the fine stone.
Others go further by giving the stones following one another a different shape. In particular, the following procedure from an experienced man is very advantageous.
You should give the coarsest stone a convex/curved shape, the next one to a lesser degree. Only the third (last) stone must be completely flat.
I just think that honing on the convex stones will require even more skill which is even difficult enough on a flat stone.