Guides
How often should you sharpen a kitchen knife?
The short answer: hone a kitchen knife weekly, or before any serious cooking session, and sharpen it on a whetstone two or three times a year in a home kitchen. Honing keeps the edge straight; sharpening puts back the metal that has worn away. If a ripe tomato skin stops giving way to the weight of the blade, it is time for the stone.
Honing and sharpening are two different jobs
An edge is a very thin strip of steel. In use it bends over in microscopic waves, so the knife feels dull even though the edge is still there. Honing on a ceramic rod or steel pushes it back into line. It removes almost no metal and takes a few seconds.
Over months, the edge also wears and rounds off. No amount of honing fixes that. Sharpening on a whetstone grinds a fresh edge by removing a little steel from each side. It takes ten to twenty minutes and is worth doing properly. More on the difference in do I need a honing steel?
How often, at a glance
| How you cook | Hone | Sharpen on a stone |
|---|---|---|
| A few times a week | Weekly | Twice a year |
| Every day | Before each session | Three or four times a year |
| Every day, lots of veg prep | Before each session | Every two to three months |
Harder steels (around 60 HRC and above) hold an edge longer, so they sit at the slower end of each range. Softer German-style steels need honing more often.
Three tests to tell when a knife needs sharpening
The tomato test. Rest the edge on a ripe tomato and draw it back gently without pushing down. A sharp knife bites into the skin straight away. A dull one skates across it.
The paper test. Hold a sheet of printer paper by one corner and slice down through the edge. A sharp knife cuts a clean, quiet line. A dull one tears or snags.
The onion test. If the knife slips on the shiny skin of an onion instead of biting in, the edge has gone.
Try a few strokes on the honing rod first. If the knife passes the tests afterwards, it only needed honing. If it still fails, it needs the stone.
How to sharpen at home
Soak or wet the whetstone as directed and set it on a non-slip base.
Start on the coarser side, 1000 grit, at the knife's edge angle (about 15 degrees for most Japanese-style knives).
Work the whole edge, heel to tip, until you can feel a slight burr along the opposite side.
Repeat on the other side.
Move to the finer side, 6000 grit, and use lighter strokes to polish the edge and remove the burr.
Rinse, dry and test on paper.
The full walkthrough is in how to sharpen a knife with a Season whetstone, and what whetstone grit do I need? explains the numbers.
The Season tools for this
The Season Whetstone with Bamboo Base (£35) has a 1000 grit side for sharpening and a 6000 grit side for finishing. The stone is 18 x 6 x 3cm on a non-slip bamboo base. Hand wash it. If holding the angle is the hard part, the Season Knife Sharpening Guide (£6) clips to the spine and holds the blade at about 15 degrees. For weekly honing, the Season Ceramic Honing Steel (£25) suits hard Japanese-style blades.
Not sure which method suits you? Whetstone, steel or pull-through compares all three.
Questions people ask
Can you sharpen a knife too often? Yes. Every sharpening removes steel, so a stone every week shortens the knife's life. Hone often, sharpen when the tests say so.
Why does my knife go blunt so quickly? The usual causes are glass, stone or ceramic boards, the dishwasher and knives loose in a drawer. See how to look after a good kitchen knife.
Is a pull-through sharpener good enough? It is quick and better than a blunt knife. A whetstone gives a finer, longer-lasting edge, especially on hard steel.
Is a sharp knife safer than a blunt one? Yes. A sharp knife goes where you tell it. A blunt one needs more force and is more likely to slip.
Cook like it matters.
From the cooks at Season, a London cookshop since 2005.