How to Sand and Seal a Wooden Deck Railing for Weather Protection (120–320 Grit Sequence)

Deck railings face as much environmental stress as the deck surface itself—sun, rain, and seasonal temperature changes all take their toll. Over time, railings can become rough, splintered, and faded. Sanding and sealing them not only improves appearance but also protects against moisture damage and extends their lifespan. In this guide, we’ll go step-by-step through sanding from Grit 120 to Grit 320 for a smooth, long-lasting finish.

Why Sanding is Important for Deck Railings

Outdoor railings are often touched daily, so splinters and rough spots can be a safety hazard. Sanding levels out imperfections, removes old finish, and prepares the wood for sealing. Without proper surface prep, sealants won’t adhere well and can peel prematurely.

Tools & Materials

• Orbital sander for flat railing tops
• Sanding block or sponge for spindles and curves
• Vacuum and tack cloths
• Multiple grits of sandpaper
• Exterior wood sealant
• Brushes or applicators
• Protective gear: mask, gloves, goggles

Best Grit Sequence for Deck Railing Refinishing

• Grit 120 — Removing old finish and smoothing rough areas
• Grit 180 — Refining the surface
• Grit 220 — Pre-seal smoothing
• Grit 320 — Optional final pass for an extra-smooth feel

Step-by-Step Process

1. Prep the work area. Remove any decorations or attachments from the railing. Cover nearby plants or furniture to protect from dust.
2. Initial sanding. Start with Grit 120 (100-pack) to remove weathered wood, flaking finish, and surface splinters. Work along the grain for best results.
3. Surface refinement. Switch to Grit 180 (10-pack) to smooth the surface further and erase scratches left by the coarse grit.
4. Pre-seal smoothing. Use Grit 220 (25-pack) to prepare the wood for optimal sealant adhesion.
5. Optional final pass. For a luxurious feel, sand lightly with Grit 320 (50-pack) before sealing.
6. Dust removal. Vacuum thoroughly and wipe with a tack cloth to eliminate all sanding dust.
7. Apply sealant. Brush or wipe on your chosen exterior sealant according to the manufacturer’s instructions. Apply evenly, allowing for full penetration into the wood grain.
8. Drying and second coat. Let the first coat dry completely, then apply a second for maximum weather resistance.

Special Cases

For railings made of softwoods like cedar, use lighter pressure to avoid excessive material removal. For hardwoods like ipe, spend extra time in finer grits for a smoother finish.

Pro Tips for Success

• Sand spindles and balusters by hand with a sanding sponge for better control.
• Work in the shade to prevent the sealant from drying too quickly during application.
• Wear gloves to keep oils from your hands from contaminating the surface before sealing.

Aftercare

• Inspect the railing annually for signs of wear and reapply sealant as needed.
• Clean with mild soap and water—avoid harsh chemicals.
• Repair small scratches promptly to prevent deeper weather damage.

FAQs

• Can I stain instead of sealing? Yes—just ensure you follow the same sanding process for best adhesion.
• How often should I reseal? Every 1–3 years depending on climate and exposure.

Watch & Learn

By following this grit progression—from Grit 120 (100-pack) to Grit 320 (50-pack)—you’ll achieve a railing that looks great, feels smooth, and stands up to the elements for years to come.