The water trough has running water fed from a stream so is continually flushing away the swarf and slurry from the stones. This sharpening trough was set up on the edge of our tea house worksite in Japan and the Japanese carpenters would visit regularly to keep a perfect edge on their tools. I have been sharpening with waterstones in the UK for many years but I learned a lot from watching and working at this sharpening trough.
Most folk in the UK soak the stone and then just splash a little extra water on the surface, the running water below the stones allows the Japanese to continually sloosh water over the stones keeping the surface very open. The other big differences were the different brands of stones which cut much faster and they continually cut back the surface of the stone with a big diamond dressing plate thus exposing fresh abrasive and flattening the surface. This means the stones are very much seen as something that has a limited lifespan, like an abrasive belt on a grinder but as the stones wear thin and break they become useful as slip stones, these too are flattened regularly on the diamond plate, here is Tak honing his chouna blade with a small piece of waterstone, note the wooden bucket of water to keep the stone slooshed.
Nicola made this is a short video whilst in Japan showing finishing a plane blade on a natural waterstone, note how the edge is washed and then he feels to check all the bur is removed. Through practice they are tremendously sensitive to this and can feel tiny burs that I need strong magnification to detect. Also note the stone is washed and put away, the Japanese are very tidy and they want that stone to be ready to use next time.
Japanese tool sharpening from Nicola Wood on Vimeo.
At the Kesurokai event in Germany 2005 the Japanese carpenters did all their sharpening squatting on the ground like this. This position allows a lot of pressure to be applied, no water trough here but they kept a bucket handy to sloosh the stones and a gardeners spray bottle to keep the surface flowing.
Hannes my German friend spent 2 years as an apprentice to a master temple carpenter in Japan and when he came over and helped me build my new timber framed woodshed he also gave us lessons in sharpening with waterstones. Hannes ran sharpening courses with our friend Michail Schutte in Germany last year and I think they plan to do it again. If there was interest I could ask him to come and run a masterclass in the UK in 2011.
Bottom row, DMT extra fine, Japanese diamond stone dresser, unknown stone very like a shapton 1000, natural stone c12000, king 1000, king 4000, king 6000.
Of these stones the shaptons are far superior to the rest, the king 1000 is barely worth having, I would just as soon use emery paper stuck to a woodblock, the king 4k and 6k are reasonable stones, in fact the 6k makes a decent finish stone at not too high a price I always finished with autosol metal polish on a board after this stone. Now I follow it with the 12k natural and 16k shapton instead. The spyderco stones are OK as fine finishing stones but they do not remove metal fast and have very little feel or feedback, the knife tends to skate on the surface as if on glass where even the 16k shapton feels like it is grabbing at the metal and cutting, this allows you to feel the bevel you are trying to sharpen much better.