Natural water stones vs synthetic
In short, I would say that for vast majority of the people that the option of using synthetic stones are just as good if not better than using natural stones.
Natural stones were the only practical tools to sharpen knives or swords in ancient Japan. There are many people still believe that natural stones give unrivaled finish, but vast majority of the people won't noticed this difference nor able to take advantages of the difference. Aside from the historical and emotional aspect of using a natural stone, any natural stone has a distribution of abrasive particles, whereas a synthetic stone have much narrow distributions. Needless to say, some believe it is better one way or the other.
I would argue that synthetic stones are more than sufficient for most of us. As time goes, the synthetic stones are getting better due to technological improvement. On the opposite, the natural stone selection is getting worse due to stone depletion. Let me put it this way. If you are going to spend ~$50, then your options of synthetic stones are better than those of natural stones.
<Should we always have a natural stone as one of our finishing stones?>
Nah, I don't think so.
"Can some one explain why some one would opt for a natural stone over a synthetic sharpening kitchen knives (or swords)?"
Tradition. When sword and knife making started centuries ago, natural stone was the only option.
" What are the benefits?"
"Should we always have a natural stone as one of our finishing stones?"
IMHO, no. Modern abrasives have more consistent grain size overall and more even distribution. This is what the vast majority of people will have the most success with. If you are a multi-generational knife or sword maker, 100's of years of experience with the same 'family' stone may yield sightly better results. Of course, you have to inherit that stone because it may cost more then a lifetime of 'wages'.
I'm assuming you're talking about Japanese waterstones rather than, say, Arkansas stones, which are a different beast altogether. I'm a user of synthetic waterstones, so much of what I'm about to tell you is second hand info.
Natural waterstones tend to have a somewhat less consistent grit size, which creates an effect some people like, both in terms of how a fine stone finishes an edge and also in terms of the kind of patterns you can create in the look of the knife. They are often considered more finicky than synthetics, working better on some steels than others. They are obviously far more expensive. There is no consensus that they actually work better than synthetics, and it's generally agreed that synthetics do about as fine of a job as your skill as a sharpener will allow.
For most people interested in sharpening, I'd say a natural waterstone is an unnecessary purchase that won't necessarily lead to better results. Synthetics do a great job, they're probably more user friendly, and they're much more affordable. But there are a few sorts who I think can justify buying a natural stone (or several):
- People for whom money is not a factor. Why not, then?
- People who have already tried all kinds of synthetics in all kinds of combinations, and are forever chasing the perfect edge, or at least new and different sharpening effects. In other words, obsessed sharpening fanatics. Eventually this might lead me to try out a natural stone myself.
- People who restore traditional and valuable Japanese blades (swords especially) and tools for a living. Natural stones might allow you to create some visual effects you couldn't achieve otherwise. And anyway, some of your customers might expect you to use them.
- People who just like that kind of thing for their own reasons, Maybe you just appreciate traditional tools.
<Eventually this might lead me to try out a natural stone myself.>
I thought of getting a natural stone, but a $100 natural stone is unlikely to match a $100 synthetic stone. A >$2000 just seems too much for my skill level. In addition, unlikely synthetic stones, natural stones have no well defined parameters. So the only good way to estimate the stone is to use it in person.
Thanks for the information guys. I have decided on synthetic (e.g. Naniwa) stones. Being a beginner I don't think using an Arkansas surgical (approx 4000 grit0 would make a difference at this point.
I just noticed on an European stones site that Naniwa sells round stones (designed for long knives). Would any one know where in Canada or the US I could order them from?