Sand Teak Handrails Between Varnish Coats (320–600 Guide)

Teak handrails take sun, salt, and hands every day. Between coats of marine varnish, the right sanding routine makes the next coat bond and flow—without cutting back into bare teak or polishing the film slick. This guide gives you a disciplined, hard-backed workflow that keeps edges crisp, grain calm, and sheen even, using a tight ladder of 320 → 400 → 600.

Why sanding matters between varnish coats

When you’re recoating, you’re working the film, not the wood. Too coarse and you trench the varnish and risk burning through high spots, exposing raw teak that will drink color and look patchy. Too fine or with a soft pad and you’ll polish the surface, lowering adhesion and creating glossy bands that telegraph through the next coat. A hard backer and tight grits create a shallow, uniform matte that new varnish wets and levels on—especially on rounded rails where fingertip pressure can dish the film.

Tools

• Hard sanding blocks: a long, flat block for straight runs; a narrow one for stiles; and a tiny curved hard backer (split dowel) for rail radii
• Silicon carbide sheets: 320, 400, 600 (9×11 in)
• Masking tape (low-tack) and painter’s pyramids/stands
• Raking light or headlamp; pencil for witness marks
• Vacuum with brush tip; microfiber cloths; tack cloth if compatible with your system
• Panel wipe/dewaxer safe for your varnish brand
• Clean, natural-bristle brush or foam applicator; strainers for varnish
• PPE: respirator/dust mask, eye protection, gloves

Grit sequence

• Open & level nibs: 320 on a hard backer to knock dust, bugs, and minor orange peel without cutting to wood.
• Refine & align: 400 to erase 320 lines and even the sheen across flats and radii.
• Final pre-coat matte: 600 for a tight, uniform haze that disappears under the next varnish coat.

Step-by-step

1. Clean like a finisher. Salt, sunscreen, and teak oils sabotage adhesion. Degrease with a two-cloth panel wipe (first cloth wet, second dry). If water beads afterward, clean again until it sheets. Mask stainless bases and gelcoat edges.
2. Map with witness marks. Under raking light, lightly pencil the top arc and sides of each handrail. Those lines vanish evenly when a zone is truly addressed—your cue to stop instead of over-sanding.
3. Open at 320 on a hard backer. Wrap fresh 320 and pull long, straight strokes with the grain along the rail. Keep the block fully supported—use the curved hard backer on radii so pressure is distributed. Swap sheets the instant the cut slows; dull paper polishes. For a reliable opener that keeps the scratch honest, stock 320 Grit Sandpaper (25-pack) so you can change early rather than pressing harder.
4. Detail the ends and stanchion zones. Around stanchion bases and returns, use a tiny rigid backer so you bridge the curve. Avoid fingertip circles—they dish and create shiny halos that glare at sunset.
5. Refine to 400 to unify tooth. Change stroke angle slightly (gentle diagonal) so any lingering 320 tracks pop, then finish with straight, with-the-grain passes. Keep tape on sharp arrises through most of this step. For consistent, cool cutting across a whole set of rails, reload from a mid-quantity box like 400 Grit Sandpaper (50-pack).
6. Edge protocol. Remove the top layer of tape, then—using a worn 400 on a tiny hard backer—make one feather-light pass parallel to each edge to unify sheen without thinning corners.
7. Set the final pre-coat haze at 600. One or two even passes are enough; stop the moment the 400 pattern tightens into a fine, uniform matte. This shallow scratch helps varnish level fast and cure clear. Finish the sequence with dependable stock such as 600 Grit Sandpaper (100-pack) so the last rail sands like the first.
8. De-dust and test wetting. Vacuum with a brush tip, tack (if your system allows), and wipe with panel wipe. Lightly mist solvent (or wipe with mineral spirits if compatible) and watch for uniform sheet—beads mean more cleaning.
9. Strain and apply varnish. Strain into a clean pot. Apply in long, continuous strokes, tipping off with the grain. Keep coats thin with proper flash; heavy passes sag on rails.
10. Cure and repeat. Follow the recoat window. Between sessions, store brushes in solvent, cover the work from dew, and keep dust down. Each cycle should feel quicker as the film builds.

Special cases

First maintenance after a season: If UV has chalked the top arc or you’ve got gray teak peeking at corners, spot-seal those burn-throughs with a light varnish touch before your global 320 pass—or you’ll keep cutting back into wood.
Oily teak: Some boards exude oil after heat. Degrease twice and give a brief wipe with alcohol just before sanding; keep sheets fresh so you cut, don’t smear.
Severe runs or sags: Level with a sharp cabinet scraper held dead flat to the film, then re-enter at 320. Don’t drop to 220 on the film unless you plan to rebuild with multiple coats.
Gloss-to-satin conversions: If you’re toning sheen, stop the intercoat scratch at 400 and let the final coat be a satin varnish; use 600 only to denib that final film.

Pro tips

• Hard backing wins. Blocks bridge highs and keep rails true; foam pads and fingertips carve dishes that catch the light.
• One direction per grit. 320 straight, 400 gentle diagonal (then straight), 600 straight. Leftover lines become obvious—and removable.
• Change sheets early. Loaded paper skates and polishes, lowering adhesion and creating zebra bands.
• Mind the light. Inspect from bow and stern under raking light; what looks fine dockside can shout underway.
• Vent & shade. Work in shade or early/late light; hot rails print brush marks and flash solvents too fast.
• Log your recipe. Record grits, stroke directions, varnish brand/thinner, and recoat times so touch-ups match the rest of the boat.

Aftercare

• Avoid handling for the first 24–48 hours after the final coat; fingerprints print in soft films.
• Wash with pH-neutral soap; skip harsh cleaners that haze fresh varnish.
• If salt crystals form, rinse with fresh water before wiping—salt is abrasive.
• Plan light maintenance scuffs (400–600 on the film) and thin refresher coats mid-season rather than big overhauls at haul-out.

FAQs

• Can I start at 220 to go faster? Not between coats—you’re sanding the film. 220 risks burn-through on edges and radii. Start 320 and keep the backer hard.
• Dry or wet? Dry is cleaner on boats. If you must wet at 600, use minimal water and keep it off raw teak and seams.
• Brush or foam? Either works. Foam lays thin, even coats; bristle carries a touch more varnish and tips nicely on long rails. Practice on scrap.
• How many coats? For maintenance, 1–2 thin coats after your 320→400→600 scuff usually restores gloss and UV protection. For rebuilds, follow your varnish maker—often 6–8 total.
• What if I see shiny bands after recoating? That’s polishing from dull paper or fingertip sanding. Let the coat cure, scuff the film at 400 on a hard backer, and recoat.

Video

Closing

Teak looks premium because you treat it that way. Keep the backing hard, pressure light, and the grit ladder tight—320 → 400 → 600. Change sheets early, read the rail under raking light, and lay thin, even coats within the recoat window. Follow this plan and your handrails will glow with a deep, even gloss that shrugs off sun, salt, and fingertips all season.