Grit is the most underestimated variable in sharpening. Most people buy a stone or discs without truly understanding what the numbers mean - and end up working too long on an unsuitable grit. This guide explains what each level is for, in what order to use them, and how to maintain your abrasives so they remain effective over time.
What is sharpening grit?
Grit refers to the size of the abrasive particles on the surface of your tool – stone, diamond disc, or ceramic disc. The higher the number, the finer the particles, and the gentler and more precise the work.
The logic is counter-intuitive: a small number = coarse grit = aggressive removal. A large number = fine grit = gentle polishing.
- Coarse grit (low number): removes a lot of material quickly, leaves deep scratches. For repair and recreating a missing edge.
- Medium grit: removes scratches from the previous grit and refines the edge. The everyday working grit.
- Fine grit (high number): removes very little material, polishes the surface. For finishing and razor sharpness.
A note on JIS and FEPA standards
There are several measurement systems - JIS (Japanese standard, most common for water stones) and FEPA/ANSI (used for diamond abrasives and European grinding wheels). The numbers may differ slightly from one system to another for the same actual fineness. In this guide, we use JIS numbers, which have become the universal reference in knife sharpening.
The grit scale: from 400 to 10,000
400 Grit - Repair and bevel restoration
This is the starting grit for truly dull, damaged knives, or when you want to change the sharpening angle. It removes material quickly and leaves deep scratches that will need to be removed with the next grit.
When to use it: knife without an edge, chipped blade, first use of a new knife poorly sharpened from the factory, or changing the angle. Avoid for routine maintenance - it removes too much material unnecessarily on a knife in good general condition.
600-800 Grit - Transition
The transition grit, often overlooked but useful. It erases deep scratches from the 400 grit and prepares the surface for the 1000 grit without excessive effort. On a moderately dull knife, it can also serve as a starting grit - less aggressive than 400 but faster than 1000 alone.
1000 Grit - The universal working grit
This is the most important grit in your kit. It creates an effective edge with a slight bite - that gentle grip that allows you to cut a tomato without pressure, slice herbs cleanly, and fillet properly. The vast majority of amateur cooks don't need to go beyond this.
The 400 + 1000 duo covers 95% of common sharpening situations. This is why our rotary sharpener comes with these two grits included - it's the useful minimum, not a commercial compromise.
3000 Grit - First polish
3000 grit erases the micro-scratches from 1000 grit and makes the edge smoother. The edge slightly loses its bite but gains in cutting smoothness - less friction, more precision. Recommended if you regularly work with delicate ingredients: sushi, thin vegetables, fresh herbs.
6000 Grit - Fine polishing
At this level, you barely remove any material - you're polishing. The edge becomes very smooth and very sharp. This is the ideal grit for Japanese knives made of hard steel (Damascus, carbon) that can benefit from this level of finish. On classic stainless steel, the difference from 3000 grit will be barely perceptible in use.
10,000 Grit - Mirror finish
The highest accessible level. The edge is absolutely fine, the blade surface reflects like a mirror. This is the domain of enthusiasts and collectors - not necessarily everyday cooks. A knife polished to 10,000 grit cuts with remarkable smoothness, but this level of finish is only fully utilized on high-end steels (Damascus, 60+ HRC carbon). On standard stainless steel, the time investment is rarely justified.
The sequential order: why you don't skip steps
Sharpening is like climbing a staircase. Each grit's mission is to remove the scratches left by the previous grit - and replace them with finer scratches. If you skip a step, the coarse scratches persist beneath the surface and weaken the edge.
| Step | Grit | Mission | What happens if you skip it |
|---|---|---|---|
| 1 | 400 | Restore bevel, create rough edge | If the edge is missing, fine grits have nothing to polish |
| 2 | 1000 | Refine 400 grit scratches, create a usable edge | 400 grit scratches remain - fragile and less durable edge |
| 3 | 3000 | Polish 1000 grit scratches | Edge remains microscopically serrated |
| 4 | 6000 | Fine polishing - high-performance edge | Finish remains below steel's potential |
| 5 | 10 000 | Absolute mirror finish | Slightly inferior result - acceptable for everyday cooking |
The scratch rule: before moving to the next grit, check in glancing light that the scratches from the previous grit have disappeared. Visible streaks after 1000 grit mean you need to continue - not move to 3000 grit.
Which grit for your knife?
The type of steel and the condition of the blade determine your starting and finishing grit. There's no need to go through every level every session.
| Knife type / situation | Starting grit | Recommended finishing grit |
|---|---|---|
| Standard stainless steel knife, routine maintenance | 1000 | 1000 - sufficient |
| Standard stainless steel knife, very dull | 400 | 1000 |
| Japanese knife (santoku, gyuto) maintenance | 1000 | 3000 to 6000 |
| Dull Japanese knife or restoration | 400 | 6000 minimum |
| Damascus or carbon steel - maintenance | 1000 | 6000 to 10 000 |
| Damascus or carbon steel - restoration | 400 diamond | 6000 to 10 000 |
| New knife poorly sharpened at the factory | 400 or 600 | Depending on the type of steel |
Diamond abrasive or stone depending on the steel: diamond wheels and stones are essential for hard steels (Damascus, carbon ≥ 60 HRC) - they cut effectively without effort. For classic stainless steel and soft steel, waterstones are preferable: large volumes of soft metal prematurely wear down diamond surfaces.
Maintaining your abrasives: stones and wheels
Poorly maintained abrasives perform less effectively, yield inconsistent results, and wear out prematurely. This is the most frequently overlooked aspect – yet it directly impacts the long-term quality of your sharpening.
Waterstones: flattening is mandatory
A sharpening stone wears down with use. The central area – where you do most of your work – gradually sags, creating a convex or concave surface. On a deformed stone, the blade no longer touches the surface uniformly along its entire length: sharpening becomes uneven and the angle impossible to maintain correctly.
The sign that a stone needs to be flattened: if you place a ruler or a flat object across the stone and it wobbles or doesn't touch uniformly, the stone is hollowed out. It must be flattened before the next session.
How to flatten: rub the stone on a flattening stone (nagura) or on a flat, abrasive surface (e.g., a sheet of sandpaper attached to glass), using regular circular motions, until you get a uniform surface. Then rinse with clear water and air dry – never vertically alone or in an airtight place.
Diamond wheels for rotary sharpeners
Diamond wheels are significantly more durable than waterstones and do not deform. Their maintenance is simple but should not be neglected:
- After each session: rinse the wheel with water to remove metallic residues that accumulate in the micro-pores. These residues clog the surface and reduce abrasiveness over time.
- Never use oil: diamond wheels are used dry or with water. Oil clogs the diamond particles and permanently degrades their effectiveness.
- Storage: store wheels flat or suspended, never stacked under pressure. A slightly warped wheel will perform unevenly.
Stone wheels for rotary sharpeners
Stone attachments for rotary sharpeners can, like traditional stones, become slightly hollowed out with intensive use – especially if you always work on the same part of the wheel. The sign: sharpening becomes less consistent from one side of the blade to the other.
How to maintain them: a pass over a hard flat surface (fine abrasive sheet on a flat surface) is enough to straighten a slightly hollowed wheel. Proceed gently with circular motions. This type of maintenance is rarely necessary more than once every six months with normal amateur use.
Grit and rotary sharpener: the same logic
The progression of grits applies exactly the same way to a rotary sharpener as to a stone. The fundamental difference: the angle is mechanically fixed at 15° or 20° – you don't have to maintain it freehand. The progression 400 → 1000 → 3000 → 6000 → 10 000 remains identical.
If you're drawn to sharpening stones but are new to sharpening valuable knives, a rotary sharpener is a serious entry point. Interchangeable diamond wheels cover the same range of grits as a complete set of waterstones – with less preparation and zero risk of incorrect angles.
🗃️ Summary Table - The Role of Each Grit
| Grit | Role | Abrasion Speed | For Whom |
|---|---|---|---|
| 400 | Repair - restore the bevel | Very fast | Dull or damaged knife |
| 600-800 | Transition - remove 400 scratches | Fast | Moderately dull knife |
| 1000 | Create the effective edge | Moderate | Everyone - universal grit |
| 3000 | Fine polishing - less friction | Slow | Demanding amateur, Japanese knives |
| 6000 | High performance - sharp edge | Very slow | Japanese, Damascus, carbon knives |
| 10 000 | Absolute mirror finish | Almost none | Enthusiast - high-end steels only |
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❓ Frequently Asked Questions
Which grit should I start with for a dull knife?
For a properly maintained knife, start with 1000 grit – it's the universal working grit. If the edge is really gone or the blade is damaged, start with 400 grit. Avoid 240 grit except in extreme cases: it's too aggressive and difficult for an amateur to control.
What is the difference between 1000 grit and 3000 grit?
1000 grit creates the edge and provides an effective sharpness with a slight bite – ideal for everyday cooking. 3000 grit polishes this edge by removing the micro-scratches from the 1000 grit: the edge becomes smoother, with less friction. Most amateur cooks stop at 1000 grit; 3000 grit is for those who want a finer result, especially on Japanese knives.
Do I have to go through all the grits?
No. You start with the grit appropriate for the condition of your knife and stop at the grit that matches your desired result. A standard kitchen knife that is properly maintained does not need to go beyond 1000 grit. 6000 and 10,000 grits are for enthusiasts and high-end steels that can benefit from that level of finish.
How do I maintain a sharpening stone?
A sharpening stone will hollow out with use and must be flattened regularly with a flattening stone. Without this maintenance, the convex surface prevents uniform contact with the blade and degrades sharpening quality. After flattening, rinse with clear water and air dry.
Do diamond wheels for rotary sharpeners require maintenance?
Yes, but it's simple: rinse the wheels with water after each session to remove metallic residues that clog the micro-pores. Never use oil. Store them flat, never stacked under pressure. Stone wheels for rotary sharpeners can become slightly hollowed out with intensive use – a pass over a flat abrasive surface is enough to straighten them.
Can you go directly from 400 grit to 3000 grit?
No. The deep scratches left by 400 grit cannot be removed directly by 3000 grit – the latter is not abrasive enough for that. Passing through 1000 grit is essential to remove the 400 grit scratches before polishing. If you skip this step, the 400 grit scratches will remain under the surface and permanently weaken the edge.
