When sharpening knives, whetstones naturally get dirty and wear out. A flattening stone is typically used to level or flatten the surface of a sharpening stone. As a sharpening stone is used repeatedly, it tends to wear more in the middle of the stone than along the edges. If the sharpening stone is not kept flat, your knives and tools will develop slightly rounded edges and become much less effective at cutting.
We can flatting a sharpening stone using several methods:
- The best-known method is using a flattening stones.
- A less well-known method is using glass and silicon carbide powder.
The procedure for flattening and reviving a stone with flattening stone:
There are two basic types of flattening stones that are commonly used. Flattening stones are made out of either a solid block of silicon carbide or a meal plate with a diamond abrasive nickel plated to one surface. Regardless of the type of material they are made from, all flattening stones are made from a very coarse grit. A flattening stone made from Silicon Carbide is much less expensive than a diamond lapping plate but they also wear much more quickly. The price range for a Silicone Carbide flattening stone is typically 20-50€. Silicon Carbide stones are manufactured by companies such as Naniwa or RH Preyda.
- Determine if your waterstone is flat. A straight edge is helpful in determining if your stone is flat. Lay the straight edge across the length and width of your stone. If you can see a gap between the edge and the stone, it needs flattening. If a gap isn't visible, try holding it up to a light to be sure.
- Mark your stone. Use a pencil to mark lines on your stone. This is used to determine if your lapping plate has lapped that part of the stone. Once lapped, the pencil marks will quickly wear away.
- Both types of stones are used with a liberal amount of lubricant. The lubricant used varies depending on the type of sharpening stone that is being flattened. If you are flattening an oilstone you use oil as a lubricant and if you are flattening a water stone you use water.
- Stop periodically to see if all your pencil marks have worn away. Once the pencil marks are gone, your water stone is lapped. The straight edge used in step one can help determine if you have a perfectly flat stone.
The procedure for flattening and reviving a stone with silicon carbide:
- before leveling, it is necessary to draw a grid on the surface of the stone with a pencil moisten the surface of the glass plate with water using a spray bottle.
- We make sure that the layer of water covers the entire glass without collecting drops.
- carefully scoop up the silicon carbide with a teaspoon and pour it on the board from a small height of 5-10 cm (so that the powder does not scatter).
- spread the silicon carbide, like water, over the surface of the glass. The suspension should not be very thick, but not very thin either.
- during the leveling process, gently press the stone and make a figure-eight movement until the drawn grid disappears
Before switching to a larger grain, it is necessary to thoroughly rinse the glass and stone, wipe the table and wash your hands - this is necessary, because the ingress of coarse powder can spoil the whole result of leveling.
Be careful when handling dry fine silicon carbide powder from F400 to avoid inhalation!
Use the table below to select an abrasive grain based on your abrasive material.
