Care & Maintenance
Sanding & Surface Preparation Guide
Updated 3 min read
The short answer
Sanding is not about making wood smooth — it is about creating a uniform surface that accepts finish evenly. The grit you stop at determines how the finish looks: 120 for paint (enough tooth for adhesion), 180 for stain (smooth enough to avoid swirl marks), 220 for clear coat (glass-smooth). Skipping grits or sanding unevenly produces defects that every finish magnifies.
Grit progression by application
| Application | Start grit | Finish grit | Why this range |
|---|---|---|---|
| Paint (on raw wood) | 80 | 120 | Smooth enough for primer adhesion, rough enough for grip |
| Stain (on raw wood) | 120 | 180 | Removes mill marks; avoids swirl visible under stain |
| Clear coat / lacquer | 150 | 220 | Glass-smooth base for a film finish |
| Between finish coats | 220 | 320 | Scuffs for adhesion; removes dust nibs |
| Removing old finish | 60 | 120 | Aggressive start; finish at the level for the new finish |
| Rejuvenating an existing finish | 320 | 400 | Scuff only; do not cut through the finish |
Sanding technique fundamentals
- Always sand with the grain
- Cross-grain scratches are visible under stain and nearly invisible under paint. If you must sand across the grain (leveling a surface), finish with a pass along the grain to remove the cross-grain scratches.
- Use a random-orbit sander for flats, hand-sand profiles
- Power sanders are efficient on flat surfaces but will round over edges and destroy profiles. Profiles, mouldings and tight areas require hand sanding with a sanding block or folded paper.
- Keep the sander moving
- Dwelling in one spot creates a depression that shows under finish. Move at a walking pace, applying even pressure. Let the abrasive do the work rather than pressing harder.
- Check your progress with raking light
- Hold a light source at a low angle to the surface. This reveals scratches, swirl marks and uneven areas that are invisible under direct light. Check after every grit change.
- Vacuum between grits
- Coarse grit particles left on the surface will scratch it when you move to the next grit. Vacuum the surface and the surrounding area before switching abrasives.
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Surface preparation beyond sanding
- Wood filler for defects
- Fill nail holes, small gaps and minor dents with wood filler matched to the species. For painted work, any filler that takes paint works. For stained work, use a stainable filler — but know that filler never matches perfectly.
- Shellac as a problem solver
- Shellac seals wood unevenly, blocks odours, and provides a universal bonding surface. If a wood species is blotching under stain, a coat of shellac thinned 50% with denatured alcohol seals it enough to prevent blotching without hiding the grain.
- Deglossing for repainting
- When repainting an existing finish, sand with 150-grit to degloss and provide adhesion. You do not need to strip to bare wood — just remove the shine and create a surface the new paint can grip.
- Moisture check
- Wood moisture content should be 6–10% for interior furniture and millwork. A moisture meter costs $20–40 and prevents finishing wood that is still acclimating — which guarantees the finish will fail.
Answers
Frequently asked questions
- What is the best sander for woodworking?
- A random-orbit sander (5-inch or 6-inch) is the most versatile. It produces a swirl-free finish that is easy to sand out, and it works on both flat surfaces and gentle curves. Belt sanders are faster but more aggressive and harder to control. For profiles and tight areas, sand by hand.
- How do I remove old finish without sanding?
- Chemical stripper is the most common alternative. Apply, wait for the specified time, then scrape off the dissolved finish with a plastic scraper. It is slower than sanding but removes finish from profiles and mouldings without destroying them. Always test in an inconspicuous area first.
- Do I need to sand between coats of paint?
- Light sanding with 220-grit or a scotch-brite pad between coats of paint improves adhesion and removes dust nibs. It is not strictly required for waterborne acrylic paint, but it makes a significant difference in the final surface quality. Always sand between coats of clear finish.
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