# The Sharpening Session Hewn Shop Notes · https://hewn.build/shop-notes/the-sharpening-session AI-drafted, not yet checked: Drafted by Chip, the writing system Hewn runs on Claude, from Hewn's craft corpus. Jonathan Salomons has not read this note yet, and no outside reader has checked it. Read it as a shop note: check a number before you cut to it. Cite as: "The Sharpening Session." Hewn Shop Notes, hewn.build/shop-notes/the-sharpening-session. Drafted 2026-04-23; AI-drafted, not yet checked. --- You know when the iron is dull. You know what a sharp iron gives you. This is the part in between: how to actually do it, start to finish, for someone who hasn't built the habit yet or someone whose habit works fine but has never been written down. ## The back comes first. And only once. The flat side of the iron is your reference surface. Every bevel you grind depends on that back being flat. If it's hollow or has a wire edge rolled to it, the angle you think you're hitting isn't the angle you're getting. New iron out of the box: assume the back is wrong. Set it on your finest stone, work it until the reflection runs unbroken from heel to toe. This is the longest you'll ever spend on the back. After this, back maintenance is thirty seconds. A few strokes on the fine stone, just enough to remove the wire edge from the bevel work you just did. You're not re-establishing flatness. You're closing the loop. Old iron from an estate sale with an arc or a hump: flatten the stone first, then flatten the back. The stone is the reference. A hollow stone produces a rounded back, and the two errors compound into something neither one caused alone. ## The bevel: pick a system Two approaches. You need to know which one you're running. Primary bevel only means you sharpen the whole bevel every time. Fixed angle, typically 25° for a bench plane iron. You work until the bevel meets the back at a burr, remove the burr, strop to polish. Conceptually clean. Also means more metal removal per session, so the sessions run longer. Secondary bevel, sometimes called a micro-bevel, means you establish the primary once on a coarse stone and then maintain only a small steeper bevel at the tip. The contact patch between iron and stone gets shorter. Faster honing, less pressure, more consistent results. The trade-off: every several sessions the secondary gets wide enough that you need to return to the primary and reset. How often depends on what you're planing and how dull you let things get before you stop. Both systems work. The secondary bevel is more common in practice because of the speed at the honing stage. What matters is knowing which one you're in so you know when the primary needs attention. ## The progression Coarse to fine. The coarse stone does the geometry work, establishing the bevel angle and removing metal to a consistent scratch pattern. The medium stone refines those scratches. The fine stone polishes the bevel until the surface reflects. The burr is your checkpoint. After the coarse stone, run your thumb across the back of the iron at the edge. Across, not along. A burr means the bevel has met the back. No burr means you haven't reached the edge yet. Uneven burr means uneven contact: one side is ahead of the other. Adjust your pressure or your body position. Not your grip. The burr comes off on the fine stone and the strop. When it's gone, you're done. ## The strop Leather charged with a polishing compound, or plain leather for a mid-session touch-up. Fastest tool in the system and the most misused. Trailing strokes only. Pull away from the edge, never into it. The compound burnishes the edge to a keenness the stones don't reach alone. What the strop cannot do: fix geometry. Drifted bevel angle, a nick from a staple, a dull flat from a mineral inclusion in the wood. The strop doesn't touch any of that. The thumbnail test tells you which tool you need. If the edge skates across your thumbnail, strop. If it catches and bites, go to the stones. During a session, the strop is often the only sharpening you need. A few strokes realigns the micro-wear from a few passes on wood. That's a sixty-second touch-up versus a five-minute session. The thumbnail test sorts it. ## Bevel-up: same mechanics, different math Everything above assumes a standard bevel-down bench plane. On a bevel-up plane, the effective cutting angle is the bed angle plus the bevel angle rather than the bed angle alone. A low-angle jack with a 12° bed and a 25° bevel gives you 37° effective. The same iron at 38° gives you 50°, which is York pitch territory on a bevel-down plane. The sharpening mechanics don't change. The angle arithmetic does. If you're working bevel-up, track your numbers deliberately. Don't just sharpen to muscle memory. ## The shape of the time Flatten the stone if it needs it. Two minutes now saves fifteen next session, because a hollow stone produces a rounded bevel that compounds into a geometry problem. Check the back. Three strokes on the fine stone confirms it's flat and clean. If it isn't, that tells you something about what's been happening to your edge. Primary bevel if needed. Secondary bevel or straight bevel to the fine stage. Burr check. Fine stone until the scratch pattern is consistent. Back at the fine stone, three strokes. Strop, ten strokes each side. Thumbnail test. Catches: repeat the last stone stage and strop again. Skates: iron goes back in the plane. Touch-up run: five minutes. Full re-grind: twenty. New iron with a neglected back: however long it takes. Do it once, don't rush it. That session sets the baseline for every sharpening after. One more thing. Bigleaf Maple dulls an iron faster than almost anything you'll work regularly. The minerals in the fiber act like a fine abrasive. Start a BLM session with a fresh edge. Expect to strop more often. Don't be surprised if you need a full session mid-board. The iron gives you the surface. The sharpening session gives you the iron. Spend the five minutes. The wood knows.