Understanding Grit Progression

Abrasive grit numbers describe particle size: lower numbers remove material faster; higher numbers leave finer scratches. On bare wood being prepared for a clear finish, visible scratches from coarse grits reflect light differently from finely sanded surfaces, creating streaks under transparent coatings.

For antique furniture, a typical progression on solid wood runs:

  • 120 grit — initial flattening after stripping; removes raised grain, stripper residue, and minor surface damage.
  • 150 grit — removes 120-grit scratches; refines the surface further.
  • 180 or 220 grit — final pass before first finish coat.
  • 320 grit or fine steel wool (0000) — between finish coats, used lightly to remove dust nibs.

Skipping grits — going from 80 to 220, for example — does not save time. The 220-grit paper cannot efficiently remove 80-grit scratches; the result is a surface that looks smooth but shows scratches under finish.

Hand Sanding vs. Orbital Sanders

Random orbital sanders are faster and reduce hand fatigue on large flat surfaces — tabletops, panels, drawer fronts. However, they have significant limitations on antique work:

  • Orbital scratch patterns are circular; on open-grain hardwoods like oak or ash, circular scratches in the grain valleys are difficult to remove with subsequent grits.
  • The pad pressure is difficult to control near edges, where wood wears faster and profiles can round over within a few passes.
  • Sanders cannot reach carved detail, coves, beads, or moulded profiles.

Hand sanding with a backing block — a firm rubber or wood block cut to fit the surface — gives direct pressure control and keeps sandpaper flat. On flat surfaces, always sand parallel to the grain. On curved profiles, wrap the sandpaper around a dowel or shaped block that matches the profile.

Detail and Carving

Carved detail requires sandpaper folded to a point, small wooden picks wrapped with sandpaper, or purpose-made profile sanding sticks. The objective is to clean the surface without removing the crisp definition of the carving. One pass with a folded edge of 150-grit across a carved rosette can remove decades of accumulated residue without altering the profile.

Practical method: Cut sandpaper into narrow strips and use them in a shoe-shine motion along curved spindles and turnings. This maintains even pressure around the circumference and avoids flat spots.

Working with Veneer

Victorian and Edwardian furniture frequently used veneer — thin slices of figured wood applied over a structural substrate. Veneer thickness on 19th century pieces is typically 1 to 3 mm, considerably thicker than modern commercial veneer. Even so, aggressive sanding can sand through to the substrate, which is irreversible.

On veneered surfaces:

  • Begin with 150 or 180 grit, not 120. The goal is to clean the surface, not remove significant material.
  • Sand with the grain of the veneer only.
  • Apply consistent, light pressure — do not press harder over dark spots or stains, as this removes more veneer than the surrounding area.
  • Stop if the wood colour changes dramatically or if the substrate grain pattern begins to show through; these indicate the veneer face is nearly exhausted.

Bubbled or loose veneer should be reglued before sanding. Sanding over a bubble will sand through the high point of the bubble first, creating a hole. Use hide glue and a veneer hammer or weighted caul to flatten loose veneer, then allow 24 hours of curing before sanding.

Grain Raising and Water Popping

Wood grain raises when exposed to water — including water-based finishes. After sanding to final grit, wiping the surface with distilled water (water popping) raises the grain intentionally before the finish is applied. The raised fibres are then sanded flat with the final grit, leaving a surface that does not raise further when the first water-based coat is applied.

This step is particularly useful when applying water-based dye stains, which raise grain aggressively on open-pored species. On closed-grain species like maple or birch, the effect is less pronounced.

Managing Sanding in Canadian Workshop Conditions

Workshop humidity significantly affects sanding results. In a cold Canadian winter, a heated workshop may drop to 20% relative humidity. Wood at this moisture level is drier than its equilibrium state and may feel rougher to sand than the same piece in spring or summer. More importantly, pieces sanded in very dry conditions and then moved to a more humid environment may show grain raising when the first finish coat is applied — even with a non-water-based finish — as the wood absorbs ambient moisture.

Maintaining workshop humidity between 35% and 50% relative humidity where possible produces more consistent results. A basic digital hygrometer mounted at work surface height provides sufficient monitoring.

Dust extraction: Sanding antique furniture generates fine hardwood dust that accumulates in lungs over time. Use a dust mask rated N95 or better, and connect sanders to a dust extractor rather than relying on shop ventilation alone. NIOSH maintains current data on wood dust exposure limits: cdc.gov/niosh.

Final Inspection Before Finishing

Before applying any finish, inspect the sanded surface with a bright light held at a low raking angle. This reveals cross-grain scratches, mill marks in the wood, and uneven areas that normal overhead lighting conceals. Any visible scratches at this stage will be more visible under finish, not less.

Wipe the surface with a tack cloth or clean cotton rag lightly dampened with mineral spirits. This removes dust and reveals how the grain will appear under a transparent finish — useful for deciding whether to apply a stain or proceed directly to clear coating.