Okudo gousa #320

Scarce Ozaki Gousa kamisori toishi. This buttery smooth gousa type tomae stone
has a perfect complexion with a faint cloud pattern. A scarce or even rare formation,
the gousa stones although gray have a white slurry. This is not a "slate" stone, it is in every
way a Kyoto Umegahata awasedo, it is the binders that give it the rich gray color, the grit
particles are exactly like any of the other Kyotos stones. I have shaved off of this stone and
the results were perfectly fine, smooth and comfortable. The one side has cut corners but
the even side is a generous 195mm long stretch to work off from.

All of my stones come fully lapped with beveled edges unless otherwise noted.

This stone and the other kamisori toishi on my site are from a world class private
collection of over 400 pieces assembled in Japan over the past years in the area around
Toyama by a collector of shaving implements. I was lucky enough to purchase total collection
over the last 2 years. Many of the hones were actually used by barbers, some dating to
the 1920s or earlier, while others were simply prepared by the miners as razor hones
as evidenced by the size and fine quality of the stones grit composition.
Grit Fineness
Size 195-72-20
Price  $245 SOLD

    Japanese Natural Stones sharpening characteristics.

    H or Hardness Scale Explanation.
    H Level 6-8 is medium hard and these stones will self slurry under a blade with pressure.
    A drop of water placed with a finger tip will sit proud for one minute and then begin to
    flatten and seep into the stones surface, within five minutes the drop will be gone.
    When using a diamond plate (DP) to lap or make a slurry the action is easy and fast.

    H Level 9 is hard and requires concerted pressure and effort upon the blade to self slurry.
    A drop of water will sit proud for one half hour and then begin to soak into the surface.
    With a DP the stone feels hard and the slurry is thin even with 10 strokes.

    H Level 10 stones are the hardest and will not self slurry even under extreme hand
    A drop of water will sit proud and round on the surface for one hour or more.
    A DP glides over the stone, abrasion happens but very slowly and only with much

    PS or Particle Size Scale Explanation.
    PS Level 1-3 (500 to 2,000 grit) for bevel creation are best found in synthetic stones
    or with greater difficulty using Arato coarse stones from Japan from areas outside Kyoto
    or from individual or successive nagura types stones with appropriate grit levels.
    At this grit level steels will brighten but with dull finishes. With laminated blades some
    contrasting finishes can be created especially if slurries are utilized.

    PS Level 4-6 (2,000 to 4,000) leave medium deep scratches that are easily removed.

    PS Level 7-8 (4,000 to 8,000) leave finer scratches that are easy to remove and
    to see with the naked eye but can be seen with a quality 15x loupe. These stones can
    a high carbon steel blade looking like polished aluminum to dull chrome.

    PS Level 9-10 (8,000 to 25,000) leave the finest scratches at the lowest levels ie. 8k to 12k
    of particle size are difficult to see with 15x, under most optical microscopes at 100x are    
    easier to see. The scratches at 12k to 25k or natural stones judged to be on par with
    these grit levels are difficult to see beyond the 15k level with most optical glass.
    The carbon steel or stainless will be bright and polished like a mirror.   

    S or Cutting Speed Scale Explanation.
    S Level 1-5 at the lowest level have no abrasion power but instead act as burnishing
    stones and the upper 5 Level are very slow to abrade tough steel.

    S Level 5-7 will cut steel and remove previous scratches easily.

    S Level 7-9 will cut steel and remove previous scratches easily and quickly.

    S Level 9-10 will excel in the above and at the 10 level will amaze.
    Cutting speed can be quantified for personal reference by stroke count.

    Japanese Stone Sizes Explanation
    Stone sizes in Japan are in millimeters and referred to as "grades" and the sizes stated are
    the minimum dimensions which takes into account variables in Length and Width only.
    This grade system has its roots at the mine entrance, and is based on a working adults
    ability to carry a certain number of grouped and graded by size stones down an average  
    mountain trail on his/her back to the valley floor. Working adult refers to a man of average
    strength. Women and children also labored but some adjustments of course made.
    Grade             Length     Width              Equivalent in inches.
    #24 pieces     210mm       78mm             8.26         3.07
    #30                205             75                  8.07         2.95
    #60                185             70                  7.67         2.75
    #80                180             63                  7.08         2.48
    #100              160             58                  6.29         2.28
    Razor            136              82                  5.35         3.22
    Koppa            are by definition bits & pieces and are usually in small sizes

    Sharpening Characteristics Explanations.

    If all things are equal: a grit rich or silica rich stone will remove a measured amount of
    steel faster than a grit poor stone will.
    A soft grit rich stone will remove a measured amount of steel faster than a grit poor hard
    Like wise if all things are equal: a coarse stone will remove a measured amount of steel
    faster than a finer stone will.
    In the same vain a slurried stone will remove steel faster than a non slurried stone will.
    And again a stone used under running water (that rinses away any loose grit/slurry
    particles) will act finer than a stone with standing water, with or without a slurry.

    Japanese natural sharpening stones are unique in the world of sharpening for handfuls of
    reasons and one of those is their ability to take on different characteristics while in a state
    of being used dry, wet, with a slurry or under running water like at your kitchen sink.

    One example of this would be that if any one particular high Hard Level Jnat (Japanese
    Natural) is used dry and without water their sharpening qualities are diminished and they
    will act more like a burnishing stone, but if that same high hardness level stone is used wet
    it will act as an abrasive stone. The same goes for coarse stones. Japanese awase-do
    (aka awase-to, tennen toishi) really only cut with advanced actions when wet.

    And about to slurry or not to slurry. A slurry comprised of loosely bound grit particles
    suspended in water, often acting as bundles of bound grit will act coarser and cut faster
    strictly depending upon the mechanical action that created the slurry. A #400 diamond
    plate will make a coarser acting slurry than a #1200 diamond plate. A nagura or slurry
    stone cut from a similar piece of tennen toishi can if harder than the base stones
    encourage the base stone to contribute slurry more freely, or if the nagura is softer it will
    itself provide the majority of slurry particles. This is the principle for which the Nagura
    Progression System is based and this system will only work marginally well with other base
    synthetic or natural stones like Coticules, Arkansas and the other slate stones.The
    Japanese dedicated natural nagura tend to favor being paired with the natural awasedo
    found near Kyoto because both the base and nagura components will encourage the
    crush of the clays that release the silica grit of each other.

    In all the world the Japanese tennen toishi are unique because of the slurry component
    and the way it can be exploited. For centuries the clay binders that comprise the glue that
    holds the stones grit in place has been manipulated by sword polishers, carpenters and
    barbers to suit their needs and requirements. No other stone will react with such
    characteristic and predictable ways as the natural stones that the mountains in and
    around Kyoto offer.

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                        cannot be duplicated without written permission