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Iyo Kogyosho

Shoma Ceramic Iyo Whetstone

Shoma Ceramic Iyo Whetstone

$79.00 USD
$79.00 USD
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The Shoma Ceramic Iyo Whetstone by Iyo Kogyosho bridges the precision of modern engineering with the tactile warmth of natural stone. Developed over five years of dedicated research, it blends finely ground powder from natural Iyo whetstones with carefully formulated clay to achieve a remarkably stable sharpening experience. Though classified as synthetic, its texture closely resembles that of natural stone—offering smooth glide, responsive control, and balanced abrasion. The composition ensures consistent feedback and a soft, mist-like finish reminiscent of kasumi polish. Designed for those who seek the natural sharpening sensation without variation, the Shoma Ceramic Iyo Whetstone represents Iyo Kogyosho’s pursuit of innovation rooted in the enduring spirit of traditional craftsmanship.

Detail

Size: W 7.5in x L 2.6in x H 1.2in / W 19cm x L 6.5cm x H 3cm
Material: Ceramic

Care ＆ Use

Safety

  • Sharpen with care and keep hands and fingers clear of the edge at all times. Improper handling may result in injury.

Before use

  • Soak the whetstone in clean water for 5 to 10 minutes before use to allow the stone to absorb water fully. Do not soak longer than necessary.

During sharpening

  • Always keep the stone surface flat and maintain a consistent sharpening angle. Apply pressure only when sharpening away from the edge. Never push the blade into the stone.
  • Select the appropriate stone based on the condition of the blade.

Double bevel sharpening

  • Begin by resting the blade on the stone at a 45 degree angle. Place your hands and fingers on the blade for stability.
  • Raise the spine to approximately 14 degrees, equivalent to the height of two small stacked coins.
  • Using moderate pressure, sharpen in straight strokes from the bottom to the top of the stone, gradually working along the entire edge. A burr forming on the opposite side indicates the edge has been established.
  • Flip the knife and repeat the process, adjusting hand placement accordingly, until the burr is fully removed.

Single bevel sharpening

  • Rest the blade on the stone at a 45 degree angle and position your hands on the blade.
  • Lay the blade flat against the stone, matching the existing bevel angle.
  • Sharpen with steady strokes until a burr forms on the opposite side.
  • Turn the blade over, keep it flat, and raise the spine slightly. Using only the weight of the knife, sharpen gently to remove the burr.

Finishing

  • For a final refinement, deburr lightly using a leather or denim strop if desired.
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Iyo Toishi: A Rare Natural Whetstone from Japans Western Region

Iyo Toishi is a natural whetstone historically quarried in the Iyo region of present day Ehime. Used for generations in blade sharpening and tool maintenance these stones were valued for their reliable and controlled performance rather than speed. Their geological composition produces a fine and stable abrasive that allows gradual steel refinement with clear tactile feedback.

The defining characteristic of Iyo Toishi is its balance. The stone removes material evenly while supporting precise edge control making it well suited for finishing stages and careful sharpening work. This consistency made it a practical choice for craftsmen who required repeatable results across different blade types.

What sets Iyo Toishi apart today is scarcity. Quarrying has largely ceased and authentic stones are increasingly difficult to obtain. Each piece reflects regional geology and a long tradition of practical craftsmanship. For those seeking natural sharpening stones with historical depth Iyo Toishi represents quiet function shaped by time and use.

Brand History

Established in 1976 in Tobe, Iyo Kogyosho was founded on a conviction that the heritage of Iyo-to should not disappear with the passing of time. When the original quarries fell silent, the company undertook the task of reviving the stone once revered as the “thousand-year whetstone.” Through careful geological research and restoration of traditional extraction methods, Iyo Kogyosho succeeded in reintroducing authentic Iyo-to to the modern era.

Led by Kunzo Irifune, the company continues to mine, refine, and process local stone, preserving both its physical and cultural lineage. Its signature brand, Shoma, blends natural Iyo-to powder with modern materials to achieve a stable, consistent sharpening experience—one that retains the warmth and responsiveness of genuine natural stone.

Beyond craftsmanship, Iyo Kogyosho’s work reflects a broader mission: to reconnect contemporary makers and chefs with Japan’s geological past. Each stone represents a dialogue between nature and human touch, a continuation of a tradition that began more than a millennium ago in the soil of Tobe. Through its quiet revival, Iyo Kogyosho ensures that the feel of natural Japanese whetstone—a harmony of earth, water, and steel—remains part of everyday craft for generations to come.