Sanding Teak Handrails Between Varnish Coats

Few things look as timeless as a yacht or runabout with deep, candy-gloss teak. That gloss doesn’t come from one thick pour; it’s built in thin, even coats—and the secret to getting them to stack level and crystal clear is disciplined sanding between coats. This guide focuses on the small but fussy surfaces of teak handrails, where curves, screw plugs, and exposed edges make it easy to burn through or leave scratches that telegraph under varnish. Follow the sequence below to scuff for adhesion, flatten dust nibs, and keep profiles crisp while you work in a marina, driveway, or shop.

Why sanding between coats matters

Varnish flows and levels as it cures, but dust, bugs, and tiny sags still show up. If you simply add more coats on top, you can trap defects and risk adhesion failures. A uniform, shallow scratch—fine enough to disappear after the next coat, but coarse enough to give mechanical tooth—lets each coat bond and flatten the last. On teak specifically, sanding also knocks down raised grain from solvent or water exposure and keeps edges from piling up into ridges.

Tools & supplies

• Hard sanding blocks: one straight, one small/curved for rail profiles
• Silicon carbide wet/dry sheets (9×11 in): 220, 320, 400, 600 (optional for denibbing)
• Masking tape (low-tack) to guard hardware bases, caulk seams, and deck paint
• Grease pencil for witness marks; bright raking light or headlamp
• Tack cloths or microfiber, vacuum with brush tip
• Solvent per your varnish system (e.g., mineral spirits) for final wipe
• Drop cloths and a clean, shaded work area; PPE: respirator, eyewear, gloves

Recommended grit sequence

• Level & fix defects: 220 grit—used sparingly to flatten runs or dust ridges without changing rail shape.
• Between-coat scuff: 320 grit across the field for uniform, adhesion-friendly tooth.
• Final tune-up: 400 grit to align the scratch before the next gloss coat or for a premium final build.

Step-by-step

1. Let the previous coat fully cure. Follow your varnish’s data sheet for recoat times. A fingerprint-hard film sands cleanly; too soft and the paper clogs, leaving drag marks and rolled edges.
2. Mask smartly. Protect adjacent gelcoat/paint and hardware bases. Run tape just shy of crisp breaks so you can remove it for one final feathering pass that preserves sharp lines.
3. Map defects under raking light. Circle nibs, sags, and bug tracks with a grease pencil. Lightly scribble witness marks along the rail—they’ll disappear when an area is uniformly abraded.
4. Level isolated flaws with 220. Wrap a small hard block and make a few targeted passes to knock down runs or nibs. When you need fresh sheets that cut consistently without gouging, reach for 220 Grit Sandpaper (25-pack). Keep strokes short and flat; do not dig with fingertips.
5. Scuff the field at 320. Switch to a longer block that matches the straight sections. Sand with light, lengthwise strokes and keep the block fully supported around curves. You’re looking for an even, satin matte with no glossy islands. Vacuum often and rotate to a fresh face.
6. Maintain pace with ample sheets. For multiple rails or a full set of handholds, stock up on 320 Grit Sandpaper (50-pack) so you never push a dull sheet that burnishes the film instead of cutting cleanly.
7. Finish alignment at 400. Make a brief, uniform pass to tighten the scratch. Use straight, overlapping strokes along the rail. Stop the moment 320 lines are gone—over-sanding polishes the surface and can reduce adhesion.
8. Batch consistency counts. If you’re building six, eight, or more coats across the whole boat, keeping finish uniform is everything. Finishing this step with 400 Grit Sandpaper (100-pack) ensures each section gets the same cut from first rail to last.
9. Edge protocol. Sand flats first, then edges. With a worn sheet folded over a tiny block, kiss outside edges with one or two passes; that’s enough to dull the sheen without chewing through.
10. De-dust and solvent-wipe. Vacuum, tack, then wipe with your system’s approved cleaner. Let solvents flash. Any residue will telegraph as fish-eyes or cissing in the next coat.
11. Recoat thin and even. Flow varnish on in long, continuous strokes, maintaining a wet edge. Avoid flooding rail tops—build gloss in layers. Observe recoat windows; if you miss one, scuff again before continuing.

Special cases

Open screw plugs and seams: These sand faster—guard with a wrap of tape and touch them last with minimal pressure.
Weathered teak returning to gloss: After initial fairing and sealing coats, step into the 320→400 cycle; reserve 220 for fixing isolated defects only.
High humidity or cool evenings: Varnish can stay soft longer. Extend cure time before sanding and keep abrasive changes frequent to avoid loading.
Matte rub-rail look: Stop at 320 and apply a satin topcoat; for gloss show finish, keep stacking thin coats, scuffing 320→400 each cycle.

Pro tips

• Work in shade and out of wind. Wind adds nibs; sun flashes solvent too fast.
• Use hard backing to keep profiles crisp; soft foam rounds over radiuses and chews corners.
• One direction per grit: e.g., lengthwise at 320, slightly diagonal at 400 to verify removal—finish lengthwise again.
• Change sheets early. A dull, loaded sheet skates and polishes instead of cutting—your enemy between coats.
• Feather tape lines. Pull tape for the last light pass so you don’t build a ridge along paint or caulk seams.
• Mind drips. If a fresh coat sags, let it gel, then shave the ridge with a sharp chisel held flat; scuff and continue next cycle.

Aftercare

• Rinse salt regularly and wipe with a soft cloth; salt crystals are abrasive and scratch varnish.
• Clean with mild soap only; avoid harsh solvents that dull sheen.
• Spot-repair early: de-nib at 400 and add a small brushed coat before UV and water widen the defect.
• Seasonal refresh: one or two maintenance coats each spring last longer than a full strip every few years.

FAQs

• Can I dry-sand? Yes—many pros do between coats for visibility. If you wet sand, use a very light, soapy mist and dry thoroughly before recoating.
• Is 600 better before gloss? Not usually. Over-refining can reduce adhesion for some varnishes. A clean 320→400 scratch is the sweet spot.
• What if I burn through? Stop. Seal the bare teak with a thinned varnish or sealer coat, let cure, then re-enter at 320.
• How many coats for a handrail? New wood often needs 6–8 build coats; maintenance cycles are usually 1–3 coats after a 320→400 scuff.
• Do I need to de-oil teak first? If freshly sanded teak feels oily, wipe with solvent recommended by your system. Once sealed with early build coats, normal between-coat prep is enough.

Video

Closing

Glossy, durable handrails are a product of discipline: let coats cure, scuff with the right grits on a hard backer, keep edges crisp, and lay down thin, even passes. With a 220-for-fixes and 320→400-for-everything-else approach, you’ll build depth fast, keep defects from compounding, and make the brightwork on your boat look showroom ready all season.