# The Sand Hewn Shop Notes · https://hewn.build/shop-notes/the-sand 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 Sand." Hewn Shop Notes, hewn.build/shop-notes/the-sand. Drafted 2026-04-22; AI-drafted, not yet checked. --- Sanding is not flattening. If the surface still needs flattening, put the sandpaper down and go back to the scraper and the plane. Sanding has one job: replace the tool marks the plane left with scratches too fine to see under finish, and open the fibre so the finish can grab. Done right, sanding is invisible. Done wrong, it's the first thing you notice. ## What the Grit Actually Does Every grit leaves scratches. That's not a flaw. That's the mechanism. A 100-grit scratch is deep enough to see under a coat of oil. A 220-grit scratch is finer than the wood's own cell structure. It vanishes. The grit progression replaces coarse scratches with finer ones until the marks left behind don't matter. That's why you can't skip grits. Jump from 120 to 220 and those 120-grit scratches are still there, hiding under what looks like a smooth surface. Put a coat of finish on it. Now they're not hiding anymore. On cherry and maple especially, they show as a haze across the whole panel. You sanded. You just sanded wrong. The sequence is: **100 (if needed) → 120 → 150 → 180 → 220.** Start at 100 if the flatten left plane marks or cross-grain cuts from traverse passes. Start at 120 if the smoother or scraper did clean work. Stop at 180 for penetrating oil finishes. Stop at 220 for varnish, lacquer, or waterborne. ## Raking Light Between Grits Between every grit change, hold a single light source nearly parallel to the surface. The scratches from the previous grit show as a directional sheen. When that sheen is gone and replaced by a uniform dull texture, you've fully removed the last grit's marks. Move on. If you skip this step, you're guessing. You'll find out what you missed when the first coat of finish goes on, which is the most expensive possible time to find out. ## Direction Matters The ROS is fine for working through the progression. It covers area fast and doesn't leave obvious directional scratches. But it leaves swirl marks, and those swirl marks telegraph under stain on tight-grained species. Cherry, maple, alder: if you're staining, the ROS progression has to close with a hand-sand pass along the grain at the final grit. Three or four passes per section, full length of the board, with the grain. That aligns the surface fibre and kills the swirl. On clear oil finishes without stain, this step is less critical. The penetrating finish forgives minor swirl. On painted work, don't bother. ## The Maple Problem Hard maple has a burnishing ceiling. Sand past it and the surface seals itself shut. Penetrating oil won't penetrate. Waterborne finish won't stick. On hard maple before a penetrating oil, stop at 180. Not 220. Going finer is counterproductive. The surface closes and the finish sits on top instead of soaking in. Raise the grain at 180, resand at 180, apply finish. For waterborne finishes on maple, 220 is fine, but raise the grain first and sand back at 220 before the finish goes on. You're sanding the raised grain, not the surface itself. Cherry, walnut, alder don't have this problem. They're porous enough that 220 doesn't close them. This is a maple constraint, sometimes birch. General sanding advice almost never mentions it. ## Secondary Surfaces Drawer boxes, cabinet backs, interior case surfaces. These don't need the full progression. 120 is enough for a painted interior. 150 handles a stained secondary surface. Spending the same time sanding the back of a drawer bottom as the top of a dining table is a reliable way to finish the project two weeks late. Match the effort to what the surface asks for. ## The Pre-Finish Check Before any finish goes on, one more raking light pass. Rotate the piece slowly. You're looking for cross-grain scratches you missed, plateau marks from uneven hand pressure, plane marks that survived the progression, and mill marks on secondary wood. A scratch that looks fine under shop lights looks obvious under a coat of oil. Finding it now costs five minutes. Finding it after the first coat costs stripping that coat and starting over. ## When You're Done 220 grit, or 180 on hard maple for penetrating oil. Final pass with the grain. Every prior grit resolved. Raking light clean. The surface should look unremarkable. Consistent sheen, no tool marks, grain legible. It should look like nothing happened to it. What happened to it is readiness. Everything the finish does from here, how the colour reads, whether the grain pops or goes muddy, whether the sheen is even, depends on what you just did.