Extramarise Heat Treatment: Sub-Zero Processing for Scissors

Heat treatment is one of several processes that shape a scissor’s final material properties. Some makers add sub-zero processing after quenching as part of a model-specific treatment route.

Mizutani Scissors’ Extramarise technology uses sub-zero processing (サブゼロ処理, sabu-zero shori) to push steel performance beyond what conventional heat treatment achieves. The process involves cooling blades to extreme sub-zero temperatures after the initial quench-and-temper cycle, converting residual austenite into martensite for a more uniform, harder microstructure.

Two Variants, Different Chemistry

Mizutani produces two distinct Extramarise formulations:

• Extramarise I features a higher ratio of molybdenum (モリブデン) within the alloy. Molybdenum adds toughness (粘り, nebari) and improves hardenability — the blade resists chipping under lateral stress.

• Extramarise II contains a higher amount of vanadium (バナジウム). Vanadium creates fine carbide particles that improve wear resistance and help maintain a keen edge longer between sharpenings.

Critically, the cobalt content is identical between both variants. The choice between Extramarise I and II comes down to whether the stylist prioritises resilience (I) or edge longevity (II) — not overall hardness.

What Sub-Zero Processing Changes

After quenching, some alloys can retain austenite. Cooling below room temperature can convert some of that retained structure before tempering. The result depends on the alloy, temperature, timing, and complete heat-treatment schedule; the process name alone does not establish an exact hardness or edge-life result.

This process is not unique to Mizutani or to scissors. Mizutani’s material pages describe how the company applies it to its own Extramarise formulations. Treat those statements as model-specific maker information rather than a comparison between countries, heritage, or production scale.

For a buyer, the practical next step is to confirm which Extramarise formulation the exact model uses, then compare its blade geometry, size, fit, care instructions, and service route. Edge life still varies with technique, workload, maintenance, damage, and sharpening.