White and Blue are Yasugi carbon cutlery steels from Proterial. White is close to iron and carbon; Blue adds tungsten and chromium, while Aogami Super adds more carbon and vanadium. Blue generally holds an edge longer; White generally sharpens faster and takes a very fine edge. Within each family, the number tracks carbon content, not quality. Proterial lists White #1 at 1.25–1.35% carbon with no listed chromium, tungsten or vanadium. Heat treatment and geometry matter more; a White #2 from one maker can be harder than a Blue #2 from another. Choose by sharpening habit, not label.
What #1, #2, #3 and Super actually mean
For the label vocabulary and carbon-versus-stainless distinction, see Japanese knife steel basics.
Proterial names these grades Shirogami 1 (白紙1号), Shirogami 2 (白紙2号), Shirogami 3 (白紙3号), Aogami 1 (青紙1号), Aogami 2 (青紙2号), and Aogami Super (青紙スーパー). Below, their familiar English listing names—White #1, White #2, White #3, Blue #1, Blue #2 and Blue Super—are used.
Proterial describes its figures as typical chemical composition percentages. It lists carbon at 1.25–1.35% for White #1, 1.05–1.15% for White #2 and 0.80–0.90% for White #3. The tables for all three show no listed chromium, tungsten or vanadium addition.
Blue #1 has 1.25–1.35% carbon, 0.30–0.50% chromium and 1.50–2.00% tungsten. Blue #2 has 1.05–1.15% carbon, 0.20–0.50% chromium and 1.00–1.50% tungsten. Blue Super sits outside the numbered pair: Proterial lists 1.40–1.50% carbon, 0.30–0.50% chromium, 2.00–2.50% tungsten and 0.30–0.50% vanadium. All six share the maker’s 0.10–0.20% silicon and 0.20–0.30% manganese ranges.
In Proterial’s lineup, #3 exists only in the White family and Super only in the Blue family. The numbers locate carbon content within each family; they do not rank finished knives. The numbered Blue grades also differ in tungsten and in the lower end of their chromium ranges, so the numeral is not a complete composition summary.
With comparable geometry and heat treatment, more carbon can support greater potential hardness and wear resistance, while less carbon generally favours toughness and quicker work on a stone. Those are tendencies, not achieved properties. Blue Super is the most alloyed Blue grade in this group, not a promise of the best knife.
Does Blue rust less?
Not in any way an owner can sensibly plan around. Proterial lists only 0.20–0.50% chromium for Blue #2 and 0.30–0.50% for Blue #1 and Blue Super. The maker’s figures show that these additions are only a fraction of the chromium found in stainless cutlery steel; they do not make the Blue grades stainless or justify a different care plan.
Both families remain reactive at the exposed carbon-steel edge. Food acids and moisture can discolour either one, and leaving either wet can lead to rust. Detailed patina and rust practice belongs on the carbon-steel patina page.
Is White really “sharper”?
“Sharper” often mixes up two questions: how readily a steel reaches a clean apex on the stone, and how long that apex remains useful. The grade label guarantees neither.
Sharpeners commonly report that White steel, with no tungsten or chromium listed in Proterial’s composition table, abrades cleanly and reaches a very fine apex quickly. That describes sharpening response, not sharpness supplied by the steel. A sharp edge is made by the sharpener, while the grind and thickness behind the edge strongly affect how the knife moves through food.
A well-treated Blue blade can often be brought to comparable practical keenness, although its wear-resistant composition may demand more work on the stones. In return, Blue generally keeps a useful edge longer between sessions. A poorly ground or poorly sharpened White #1 blade can therefore cut less keenly than a well-ground Blue #2 blade, regardless of what a comparison chart implies.
Which grade is kinder to a beginner sharpener?
Sharpeners commonly report that White provides the faster learning loop: it abrades readily, changes can be easier to feel, and corrections can be quicker. Raising and removing a burr can feel more immediate. The trade-off is that an otherwise comparable White edge will generally ask for attention sooner.
Blue commonly needs more strokes and more patience, but it forgives a longer interval between sharpening sessions. That can be the easier arrangement for someone who dislikes frequent maintenance. Among broadly comparable blades, sharpeners commonly report that Blue Super asks the most of the stone and holds a working edge the longest of this group.
The kinder choice depends on where friction is most likely. Someone who enjoys frequent, short touch-ups may appreciate White’s quick feedback. Someone who postpones sharpening may prefer Blue’s longer interval, provided a slower eventual session is acceptable. Blue Super suits that second habit more strongly; “Super” describes its composition, not the owner’s skill or the knife’s prestige.
Does the cladding matter more than the core?
The core governs most of the edge’s sharpening response and retention. The cladding governs much of the blade face’s reactivity, affects the feel of thinning, and contributes much of the blade’s support and toughness. These steels are usually clad so that a thin, hard carbon-steel core can form the cutting edge while tougher outer material supports it. Stainless cladding can reduce maintenance across the blade faces, but the exposed core still reacts. Construction methods, terminology and exceptions are covered in san-mai vs mono-steel.
So which one?
Start with the maintenance rhythm that is realistic. If sharpening is a regular and satisfying part of ownership, White’s quick feedback may matter more than a longer interval. If sharpening tends to be delayed, Blue may make that interval easier to live with; Blue Super generally leans further toward fewer, more demanding sessions. None of these grades removes the need for prompt wiping and thorough drying.
When two knives also differ in heat treatment, edge geometry or cladding, those differences can easily outweigh the grade label. Use anatomy of a Japanese knife to identify the other features in the comparison. Then choose the sharpening routine that will actually be kept, rather than the steel name that sounds most impressive.