Unlike oil-based whetstones, the Samura 400 waterstone is used exclusively with water. Before use, the stone is soaked in water and thoroughly rinsed during and after soaking to remove metal shavings. Oil or grease must never come into contact with the waterstone, as this impairs its sharpening function. While oilstones require lubricant to keep the pores clear, the waterstone uses water to remove particles and offers a higher material removal rate due to the faster removal of dull abrasive particles.