I've read in several places that oil should not be used on Japanese waterstones, but none of the sources explain the reasoning behind this. What, if any, damage would using oil cause and would it be reparable?

  • Was the raw chicken also covered in a thin layer of oil? I'm not sure where that enters the equation.
    – logophobe
    Commented Sep 17, 2014 at 13:35
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    @belisarius I skimmed that thread. Seems like someone has the same stone as me and oil caused knives to slip over the stone instead of being sharpened.
    – cyang
    Commented Sep 18, 2014 at 2:40
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    Send it through the dish washer. Commented Sep 18, 2014 at 15:34
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    dishwasher is a good idea. if that doesn't work, it gets complicated or expensive. 1) chemically clean it (dangerous--boil in NaOH solution in a non-aluminum pot) 2) mechanically remove the layer with the oil or 3) replace the stone with a new one Commented Oct 1, 2014 at 2:58
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    Oil is viscous, does not evaporate, and can harden into a varnish. From the sound of it, Japanese waterstones, are soft and large-pored; just the sort of thing a metal powder loaded semi-drying oil could soak into, polymerize and ruin. I use Diamond plates myself, they aren't all that expensive anymore. Commented Nov 16, 2014 at 4:35

1 Answer 1


Japanese style whetstones made of natural material, also known as "waterstones", rely on water to make a paste from the material, and this paste is abrasive and aids in sharpening. Oil is not as effective as water in making this "mud" as the stone material isn't as soluble in oil.

Further, once you have used oil on any type of whetstone, water may no longer be used as a lubricant, as it will be shed by the oil that has soaked into the stone and be ineffective in carrying away the swarf (metal abraded from the blade by sharpening).

Here is a FAQ on natural waterstones from an online retailer.

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