Which sandpapers for wood?

Start P80 (coarse), P120 (medium), P180-220 (fine). Always sand with the grain.

Sanding Wood: Which Sandpapers? | Paint Guide Oikodomisis

1. The Grit Scale: The Golden Sequence Rule

Grit scale infographic: P40-80 (coarse), P100-150 (medium), P180-220 (fine), P240-400+ (very fine). Rule: never skip grits (greek and english)

The number on the back (e.g. P80) indicates grain size/density. The lower the number, the more aggressive:

💪 Coarse (P40-P80)

Heavy removal: old varnish, paint, initial flattening of very rough wood.

⚖️ Medium (P100-P150)

Surface shaping. Removing deep scratches left by the coarse grits.

✨ Fine (P180-P220)

Preparing bare wood for primer/finish. Smooth to the touch.

🔬 Very Fine (P240-P400+)

Sanding between coats (cutting "nibs"). Final polishing.

⚠️ Never skip grits! Going P40 → P120 (skipping P60/P80) means swirl marks will only appear after the finish coat.

2. Grain Material: What Does the Sanding?

Not all grains are equal - the abrasive material determines speed and durability:

🟤 Aluminum Oxide

Brown/gold. Self-sharpening (fractures → new edges). Most popular - excellent for hardwoods and old varnish.

⬛ Silicon Carbide

Black/grey. Fastest cutting but wears quickly. The absolute choice for wet sanding between coats.

🔴 Garnet

Reddish, natural mineral. Doesn't last long, but creates the smoothest, most beautiful finish on bare wood. Ideal for final hand sanding.

🟣 Ceramic

Purple/red. Premium. Extremely hard and durable - mainly for power sanders and heavy-duty material removal on very hard woods (oak, iroko).

3. Open-Coat vs Closed-Coat

📂 Open-Coat

Grains cover 50-70% of the backing. They leave gaps for dust to escape. Essential for resinous woods (pine) or removing old finishes that would otherwise "clog" the sandpaper.

📁 Closed-Coat

100% grain coverage. Larger cutting surface, faster results, but clogs instantly on soft or gummy materials. Ideal for hard, dry hardwoods.

3. Backing: Paper, Cloth or Mesh?

What holds the grain plays a huge role, especially when working with machines:

📄 Paper

Sharp cut but tears on edges. Best for flat surfaces and finishing.

🧵 Cloth

Very durable, flexible. Sands carved furniture, railings, curves without disintegrating.

🔲 Mesh / Screen

Modern revolution: open mesh that never clogs. 100% dust extraction with vacuum. Ideal for resinous finishes/fillers.

4. The 4 Professional Secrets

Practices that separate the amateur from the professional:

✏️ 1. Pencil Trick

Draw zigzag pencil lines across the surface. Sand until they vanish = uniform result, ready for the next grit.

🔦 2. Raking Light

Turn off lights, shine a strong LED torch at a very low angle. Shadows instantly reveal every swirl mark that must be erased before the finish.

💧 3. Grain Raising

For water-based finishes: dampen with sponge → dry → P220 → cut raised fibres. The finish will now lie glass-smooth.

🧹 4. Anti-Clogging

Stearate-coated papers (white/yellow coating) triple the lifespan. Rubber cleaning stick pressed against a running belt removes clogged resin in seconds.

5. The Professional's Corner

Critical technical details:

🌊 Grain Raising

Water-based finishes swell wood micro-pores (fibres). Dampen with distilled water → dry → light P220 to "cut" fibres. Final finish on a smooth base.

⚙️ Belt Sander + Rubber Stick

Rubber abrasive cleaning stick pressed against the running belt pulls out clogged resin in seconds, saving huge consumable costs.

🔄 Swirl Marks: #1 Cause

Skipping grit numbers. A finer grit cannot erase the deep scratches left by a much coarser one. Also, excessive pressure tilts the grains instead of cutting, creating harmful friction heat.

😷 Dust Safety (PM2.5)

Fine wood dust (especially from Oak and Beech) is a known carcinogen. Use an M-Class vacuum with HEPA filtration. A simple dust mask is insufficient for the micro-particles that hang in the air.

💡 Pro Tip: Don't lean on the sander. The weight of your hand is sufficient. Pressure causes "burnishing" of the wood fibres, closing the pores and preventing the varnish from bonding.

💡 Success in sanding doesn't require force - it requires knowledge. Don't skip grits, and let the sandpaper do the work.

Wood Sanding: Which Sandpapers & When?