Flattening a worn sharpening stone

Sharpening stones can become worn and hollowed after repeated use. A worn stone may not work as effectively or it may sharpen a tool or blade unevenly. Hollowed stones also make maintaining a knife's blade at a desired angle much more difficult as you draw it across the uneven face. The guide below shows you the most common ways to flatten a sharpening stone.

Flattening stone (truing stone)

There are special types of stones available that are designed to flatten an out-of-shape sharpening stone, sometimes referred to as "truing stones". Naturally, they have a smaller grit number than the usual whetstones (from 40 to 80), in order to be harder during contact.

Lay the uneven face of the sharpening stone down upon the flattening stone.

Applying pressure with your hands, rub the stone back and forth keeping it as level as possible as you do. 

As the flattening stone begins to abrade the sharpening stone, any places where the stone is uneven will begin to recede as the stone becomes closer to flat and "true" again.

When you have finished, the stone should be perfectly flat again. Using a straight edge tool to check will help.



Laying a piece of sandpaper out on a flat board or piece of glass and then rubbing your sharpening stone will work as a simple alternative.

    Diamond stones

Using a diamond stone to flatten your out-of-shape oil or water stone is another alternative. Diamond stones (or plates) are often used to bring natural or synthetic stones back into true shape and function.

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Straightening stone ≠60 TOJIRO Straightening stone ≠60 TOJIRO


Straightening stone ≠60 TOJIRO


Straightening stone from TOJIRO, perfect for the maintenance of your whetstones. Repeated use of a whestone will wear the whetstone down, but also leave a groove in the shape of your sharpening movement. The Tojiro straightening stone with a very coarse ≠60 grit effectively puts a flat surface back on your whetsone.Instructions included in the packaging. Made in Japan.Stones to be used dry..

Straightening stone KAI


Straightening stone KAI


The AP-2455 straightening stone is equipped with an ≠80 grain, making it the optimal tool to smooth depressions or irregularities in the surface of the grindstone being used and to round off rough edges.If you are professional then you really need this tool in order to flatten your waterstone in the long term. It is the perfect tool for a regular stone maintenance...

Showing 1 to 2 of 2 (1 Pages)