# The Build Hewn Shop Notes ยท https://hewn.build/shop-notes/the-build-89 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 Build." Hewn Shop Notes, hewn.build/shop-notes/the-build-89. Drafted 2026-04-23; AI-drafted, not yet checked. --- Your first coat is dry. You ran a hand across it and it told you something. Now you need to decide how many more coats to put on top of it. Most people know the basic routine: apply a coat, let it dry, sand it lightly, apply another. But the routine isn't the knowledge. The knowledge is knowing when the routine is done. ## What each coat actually does Every coat bonds to the one below it and adds a thin film on top. Three things change as you stack coats: protection deepens, sheen evens out, and on open-grained species the pores gradually fill. On cherry or maple, two or three coats and you're there. The surface reads as finished. On white oak or ash, the pores telegraph through early coats. You can watch this under raking light. After the first coat, the pores are obvious. After the second, less so. After the third, the film over them is stable enough that it won't crack at the bridge. You're done when the finish disappears. When you pick up the piece and notice the wood, not the film over it. ## Between-coat sanding Between every coat, a light sanding knocks the dust nibs flat and gives the next coat something to grab. This is not aggressive work. You're leveling the debris that settled into the wet film and scuffing the surface for mechanical adhesion. That's it. 320-grit for most between-coat work. A fine grey Scotch-Brite pad works on flat surfaces and anywhere you're nervous about cutting through on an edge. For the last between-coat sand, before the final coat, step up to 400 or use the grey pad. Finer scratch pattern means finer adhesion marks hiding under that last coat. How you know you've sanded enough: the sheen is uniformly dull. No shiny patches. A shiny patch is a low spot or a spot you missed, and the next coat won't adhere evenly there. Tack cloth after every sand, before every coat. No exceptions. Dust nibs are almost always dust. Remove the source and you remove the problem. ## The recoat dead zone Finish dries in stages: wet, tacky, dry to touch, dry to sand. You sand at dry-to-sand. Not before. Sand a coat that hasn't fully hardened and the abrasive gums with partially cured finish. You get a rough, hazy surface that takes two coats to recover from. One mistake, two coats of rework. Waterborne finishes feel dry in thirty minutes but don't reach sandable for two to four hours at room temperature. The manufacturer's recoat window assumes 70 degrees and moderate humidity. If your shop is below 60, add time. There's no shortcut. Oil-based finishes need twenty-four hours between coats minimum. That's not a suggestion on the first coat. The oil is cross-linking, not just drying, and cross-linking takes the time it takes regardless of how the surface feels to the touch. Hardwax oil: same wipe-off discipline as the first coat. Work it in, wait for cloudiness, wipe off all excess. Two to three coats total. After three coats the wood has taken what it's going to take. ## How many coats There's no universal number. Two coats of oil-based varnish on cherry is plenty. Two coats of waterborne on ash barely starts filling the pores. Three coats of hardwax oil on walnut is often one more than the wood wants. Build until the surface tells you it's done. For furniture that takes daily punishment, tables and chair seats and drawer runners, err toward more. For display shelves and hand-tool boxes where feel matters more than armor, err toward fewer. Here's a useful test after each coat. Run your hand across it. Does the finish feel like it's protecting the wood, or does it feel like it's adding something to the wood? A finish that's found its level feels protective but not present. A finish that's still building feels slightly thick, slightly too much of itself. ## When to stop After four or five coats of most film finishes, you've passed the structural need. The finish doesn't get meaningfully more protective. Each additional coat adds application time, drying time, sanding, and one more chance to introduce a run or a sag or a dust nib that hides until the last coat reveals it. The question is always: is this coat improving the piece? When the answer is a clear yes, apply it. When the answer is "maybe," you're done. Stop before you start adding coats out of anxiety. The surface is built. Now it needs one last coat to close it out.