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Tajima #tj73004

Tajima #tj73004

$350.00 USD
$350.00 USD
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dimensions

210mm x 80mm x 45mm
Weight: 1803g

Description & Identification


Stone Type / Provenance: This is a Japanese natural medium-grit whetstone (chu-toishi), commonly referred to Tajima sourced from Hyōgo.
Color & Grain Structure: It features a light ash-grey/off-white base Matrix uniformly peppered with distinctive dark specks (goma / sedimentary mineral inclusions). The texture is characteristic of sedimentary siltstone/sandstone typical of mid-grit Japanese naturals.
Accompanying Piece: It includes a matching (Tomo nagura/Slurry stone) cut from the same stone material, useful for cleaning the surface, pre-conditioning the bevel, or raising an initial slurry.


Dimensions & Weight: 210 mm × 80 mm × 45 mm, weighing 1,803 g. This places it squarely in the full bench-stone class (comparable to standard Type 30/40 bench formats), with substantial thickness to last a lifetime of shop use

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Classification & Performance Characteristics

Category: Chu-toishi (Medium-grit sharpening stone).
Estimated Grit Equivalence: Approximately #1,000 – #1200 grit (synthetic equivalent), depending on slurry dilution, blade pressure, and surface conditioning.
Hardness:  Lv 2.5 to 3.5 (medium to medium-firm). It offers comfortable tactile feedback with decent slurry generation under moderate tool pressure, without dishing excessively fast.
Cutting & Finish Profile: Excellent toothy, semi-matte/hazy finish on cladding and core steel. It serves as an ideal intermediate step between aggressive shaping stones and fine pre-finishers (such as Aizu or fine Suita), leaving a functional working edge with aggressive bite for utility and kitchen blades.


Markings & Stamps
Grade Stamp: A distinct oval seal stamped on the side reading 特選 (Tokusen), translating to "Specially Selected" or "Choice Quality."
Origin Stamp: A rectangular boxed stamp located near the opposite upper corner on the same flank, partially weathered/faded, denoting the regional distributor mark.


Flaws, Inclusions & Structural Condition
Perimeter Chips: Small breakout chips and irregular edging along the bottom corners and bottom edge bevels (visible on the underside), typical of sawn quarry blocks that have not received an aggressive secondary chamfer.
Saw Marks: Pronounced diagonal gang-saw / wire-saw striations across the sides and underside. These are strictly cosmetic on the sides/bottom.
Toxic Inclusions / Cracks: No visible toxic quartz veins (suji), major toxic fossil pockets, or destabilizing through-cracks are apparent on the working face. The dark speckling is homogeneous and benign, contributing to slurry friability rather than gouging blade bevels.
Sealing: The stone is sealed on all sides (minus the working surface).
Valuation & Pricing

care instructions

1. Preparation & Water Management
Splash-and-Go Only: Never soak your natural finishing stone in a water bath. Prolonged submersion softens the natural binders and risks cracking or delamination along natural mineral lines.
Surface Wetting: Mist or splash clean water onto the working face just before sharpening. Add water sparingly throughout your session to maintain a slick working surface.
Bench Placement: Place the stone on a non-slip rubber base or a dedicated wooden stone holder with gentle clamping pressure.
2. Slurry Generation & Sharpening
Soft to Medium Stones (Hardness 2.5–3.5): These stones naturally release their own slurry under light blade pressure. Let the auto-generated mud do the work; do not wash it away mid-session.
b Use a diamond plate (such as an Atoma 1200), a clean Tomo Nagura, or a Mikawa Nagura to raise a thin, milky slurry in 5 to 10 light circular passes before laying your blade flat.
Pressure & Technique: Maintain light, even pressure. Allow the semi-rounded silica particles in the slurry to break down naturally—this self-refining action creates the signature toothy edge and cloudy kasumi finish.
Slurry Thickness: If the mud becomes too sticky or pasty, add a few drops of water. If it is too thin, work the stone lightly to concentrate the abrasive particles.
3. Cleaning, Drying & Long-Term Care
Rinse Clean: When finished, gently rinse off steel swarf and residual slurry using room-temperature tap water. Do not use dish soap, detergents, or hot water.
Air Dry Indirectly: Wipe the stone dry with a clean towel and allow it to dry completely at room temperature, away from direct sunlight, heating vents, fans, or freeze-thaw cycles.
Storage: Store the completely dry stone flat on a shelf in a climate-controlled room. Avoid enclosing a damp stone in an airtight plastic box.
Edge Lapping: Keep the working surface flat by lightly dressing it with a fine diamond plate (Atoma 1200 or 400) under running water when dish patterns begin to form. Chamfer the outer top perimeter edges lightly to prevent edge chipping during blade passes.

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