# How to Sharpen a Knife With Sandpaper on a Flat Surface Source: https://stoneandstrop.com/blog/how-to-sharpen-a-knife-with-sandpaper Published: 2026-10-12 Publisher: Stone and Strop Yes, you can sharpen a knife well with sandpaper: glue or tape wet/dry silicon carbide paper to something truly flat, such as glass or a granite tile, and use edge-trailing strokes only (spine first, pulling the edge behind), working from about 400 grit up to 1000 to 2000. Sandpaper cuts fast, costs little and never needs flattening, but it tears if the edge leads and wears out quickly. Here is the full setup and method, plus the mouse-pad trick for convex edges. ## What you need Use wet/dry silicon carbide paper, the black or dark gray automotive kind, not the yellow or brown aluminum oxide paper sold for wood. Silicon carbide cuts hardened steel well and can be used with water. A basic progression is 400, 600, 1000 and 1500 or 2000 grit. Add 220 if the knife is very dull or chipped. The base must be flat and rigid. A piece of float glass, a granite or marble tile, or a thick acrylic plate all work. Hold the paper down with a light spray of water underneath (surface tension grips it), spray adhesive, or tape along the edges. A strip of paper about 2 inches wide and 8 to 11 inches long, a full sheet cut lengthwise, is easy to work with. Keep the grits separate. Mark each strip on the back with its grit number and store them flat in a folder so they do not pick up coarse particles from each other. A single loose grain of 220 on a 2000 grit sheet will scratch the bevel you just refined. ## Edge-trailing strokes only On a stone you can push the knife edge-first. On sandpaper you cannot: the edge digs in and slices the paper. Always move the knife spine-first, dragging the edge behind it. Lay the blade on the paper at your sharpening angle, about 15 to 20 degrees per side for kitchen knives and 20 to 25 for outdoor knives, and pull it toward the spine side across the paper, sweeping from heel to tip. Because you only work in one direction, you lift the knife off at the end of each stroke and start again. That feels slow at first, but sandpaper cuts quickly, so the total time is similar to a stone. [Angle guides that help on paper too](https://stoneandstrop.com/best/best-knife-sharpening-angle-guide) ## Step-by-step: from 400 grit to a finished edge Start on 400 grit, or 220 if the edge is chipped. Hold the angle and make edge-trailing strokes on one side until you can feel a burr along the whole length of the opposite side. Switch sides and repeat. Then alternate sides with fewer strokes to reduce the burr. A felt-tip marker on the bevel shows whether you are hitting the edge: it should come off right down to the apex. Move to 600, then 1000, then 1500 or 2000. At each grit you only need enough strokes to replace the previous scratches, typically 10 to 20 per side, alternating at the end. Wipe the blade between grits so coarse grit does not end up on the finer paper. Finish with a few light alternating strokes on the finest grit or on a leather strop to remove the last of the burr. [Leather strops for the final step](https://stoneandstrop.com/best/best-leather-strop-for-knives) ## The mouse-pad method for convex edges Place the sandpaper on a mouse pad or thin piece of firm foam instead of glass. The paper gives slightly under the blade and wraps around the edge, producing a gently curved, convex bevel. Many axe, machete and some outdoor knives use convex edges because they are strong, and this is the easiest way to maintain one at home. Use the same edge-trailing strokes and the same grit sequence. Use light pressure: the harder you press, the more the pad deforms and the more rounded the edge becomes. Lift the spine slightly at the end of each stroke so the curve continues right up to the apex. [Stones for axes and hatchets](https://stoneandstrop.com/best/best-axe-sharpening-stone) ## Sandpaper vs whetstones and diamond plates Sandpaper is cheap, cuts fast and is always flat as long as the base is. It is a good way to try sharpening before buying stones, and it is excellent for restoring a very dull knife or flattening the back of a chisel. Its downsides are that it wears out quickly, loads with steel and must be replaced often, and that you can only stroke one way. For regular sharpening, a medium whetstone or diamond plate is more convenient over time. Many sharpeners keep sandpaper on glass for occasional coarse repair work and for flattening stones, and use stones for everyday sharpening. [Compare diamond plates](https://stoneandstrop.com/best/best-diamond-sharpening-stone) ## Common mistakes Pushing the edge into the paper is the classic one; it cuts the sheet and can nick the edge. Using worn-out paper is the second: once a section looks glazed or no longer feels gritty, move to a fresh area or replace the sheet. Third is a base that is not flat, such as a wooden table, which produces a wavy bevel. Do not skip too many grits. Jumping from 220 straight to 2000 leaves deep scratches the fine paper cannot remove in reasonable time. Steps of roughly double the grit number work well. ## Frequently asked questions What grit sandpaper is best for sharpening knives? Start at 400 for a dull knife, or 220 for a chipped one, then 600, 1000 and 1500 to 2000. For a quick touch-up, 1000 followed by 2000 is often enough. Can I use regular wood sandpaper? It works poorly. Aluminum oxide wood paper is softer and clogs quickly on steel. Wet/dry silicon carbide paper lasts longer and can be used with water. Should I use water with sandpaper? A light mist of water keeps wet/dry paper from clogging and helps hold it flat on glass. It is optional for a few strokes but helps for longer sessions. Is sandpaper sharpening bad for knives? No. With edge-trailing strokes and a consistent angle, it gives a clean, sharp edge equal to a stone of the same grit. ## Gear guides for this topic - https://stoneandstrop.com/best/best-diamond-sharpening-stone - https://stoneandstrop.com/best/best-leather-strop-for-knives - https://stoneandstrop.com/best/best-knife-sharpening-angle-guide