Sanding Wood: Grits, Techniques, and What Actually Matters

Sanding wood has gotten complicated with all the conflicting advice flying around. As someone who has sanded thousands of board feet over the years, I learned everything there is to know about getting smooth surfaces efficiently. Today, I will share it all with you.

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The goal is simple: create a surface that accepts finish evenly. The path there involves choosing the right grits, using proper technique, and knowing when to stop. Most beginner mistakes involve either skipping grits or sanding longer than necessary.

Why Sanding Matters

Probably should have led with this section, honestly. Sanding does two things: removes material and creates texture. Removing material smooths out rough saw marks, planer snipe, and surface defects. Creating texture opens the wood grain so stain and finish can penetrate evenly.

Skip the sanding and your finish will fail. Stain applies blotchy because the surface has uneven absorption. Clear coats peel because they can’t grip the surface properly. The extra hours on finishing will cost more than the time saved skipping the sanding step.

Understanding Sandpaper Grits

That’s what makes grit selection endearing to efficiency-minded woodworkers—it’s purely math. The grit number tells you how many abrasive particles fit in a square inch. Higher numbers mean smaller particles, which means finer scratches.

The practical breakdown:

• 40-60 grit (Coarse): Heavy material removal. Flattening rough lumber, removing old paint or finish, leveling glue joints. Leaves deep scratches that require extensive follow-up sanding.
• 80-100 grit (Medium-Coarse): Primary shaping and smoothing. Where most projects should start if the wood is already reasonably flat. Removes mill marks and minor defects.
• 120-150 grit (Medium): General preparation. Gets the surface close to finish-ready. Most hardwoods look good at this stage for paint-grade work.
• 180-220 grit (Fine): Final sanding for stain or clear finish. Creates the smooth surface that makes finish look professional.
• 320-400 grit (Very Fine): Between-coat sanding. Smooths finish coats and prepares for subsequent applications. Rarely needed on bare wood.

The Grit Progression Rule

Never skip more than one grit level. Each grit removes the scratches from the previous grit while leaving its own smaller scratches. Jump too far and you’ll spend forever trying to remove deep scratches with fine paper that wasn’t designed for that job.

The typical progression: 80 → 120 → 180 → 220. Some woods can skip 180 and go 80 → 120 → 220. Softer woods often need every grit because scratches show more. Hard maple tolerates skipping; pine doesn’t forgive it.

Recommended Sanding Tools

Best Random Orbital Sander

For most woodworking tasks, the BOSCH ROS20VSC 5-Inch Variable Speed Random Orbital Sander delivers excellent results. Variable speed control (7,500-12,000 OPM) lets you match the sanding action to the task—lower speeds for delicate surfaces, higher for aggressive material removal. The random orbit pattern minimizes visible swirl marks that plague sheet sanders.

The included dust collection works well enough for light sanding. Connect it to a shop vacuum for serious dust control. Woodworking dust isn’t just annoying—it’s a health hazard and a fire risk. Control it.

Best Manual Sanding Block

Power sanders can’t reach everywhere. For edges, corners, profiles, and detail work, the 3M Rubber Sanding Block distributes pressure evenly across flat surfaces. The rubber grip reduces fatigue during extended hand sanding sessions. At 2-5/8″ x 4-3/4″, it’s sized right for furniture-scale work without being too bulky for detail areas.

Sanding Sponges for Contours

Flat sanding blocks can’t follow curves. Sanding sponges conform to molding profiles, rounded edges, and carved details. Keep several grits on hand—they’re cheap enough to use freely and replace when worn.

Hand Sanding Technique

Always sand with the grain. Across-grain scratches show through any finish. Even random orbital sanders occasionally leave cross-grain marks—final hand sanding with the grain removes them.

Let the sandpaper do the work. Pressing harder doesn’t speed up sanding; it just wears out the paper faster and creates uneven surfaces. Light, consistent pressure with multiple passes beats heavy pressure with few passes.

Keep the paper moving. Dwelling in one spot digs a depression. Move in long strokes that cover the full length of the board when possible.

Power Sander Technique

Random orbital sanders are forgiving but not foolproof. Keep the sander moving constantly—parking it in one spot creates a divot. Lift it off the work before stopping the motor, or the slowing disk creates a swirl mark.

Work in overlapping patterns. Each pass should overlap the previous one by about half the sander pad width. This ensures even coverage without missing strips.

Check your progress frequently. Wipe the surface with mineral spirits to see how it will look under finish. The spirits evaporate without affecting the wood, revealing scratches, glue spots, and other issues that need addressing before you move to finer grits.

When to Stop Sanding

The finish you’re using determines how far to sand. For paint, 120-150 grit is usually sufficient—paint fills minor scratches and creates its own surface. For stain and clear finish, 180-220 grit is standard. Going finer than 220 on bare wood can actually close the grain too much, preventing stain penetration.

There’s no benefit to endless sanding. Once the previous grit’s scratches are gone and the surface is uniform, you’re done with that grit. More sanding just wastes time and sandpaper.

Common Sanding Mistakes

• Starting too fine: If the wood has mill marks or defects, start with a grit aggressive enough to remove them. Working through 220 grit won’t fix problems that needed 80 grit attention.
• Skipping grits: Going from 80 straight to 220 means you’re trying to remove deep scratches with paper designed for polishing. It doesn’t work.
• Ignoring end grain: End grain absorbs finish differently. Sand it finer than the face grain—often one grit higher—to even out absorption.
• Sanding through veneer: Plywood and veneered panels have thin face layers. Sand carefully or you’ll break through to the core.
• Wet sanding too early: Raising the grain with water works well, but do it between intermediate grits, not at the very end. Sand at 150, wet, let dry, sand at 180/220.

Dust Management

Wood dust causes health problems. Fine dust stays airborne for hours and penetrates deep into lungs. Hardwood dust is particularly problematic. Wear a dust mask rated for fine particles—the cheap paper masks don’t cut it.

Dust collection matters. Connect your sander to a shop vacuum or dust collector. Work in well-ventilated spaces. Clean up regularly rather than letting dust accumulate.

Beyond health, dust affects finish quality. Dust particles landing on wet finish create bumps and rough spots. Clean the work area thoroughly before finishing, and consider wiping pieces with a tack cloth immediately before applying finish.

The Bottom Line

Sanding doesn’t require complex technique—just patience and progression. Start with a grit appropriate for your surface condition, work through the grits without skipping, and stop when the surface is ready for your chosen finish. The time invested in proper sanding shows in the final result. Rushed sanding creates rushed-looking projects. Take the time to do it right.