Sanding vs. stripping exterior wood

What sanding is for

Sanding removes material: the oxidised grey layer, raised grain, shallow stains and surface damage. It also levels a surface so the finish reads evenly. Where a piece is weathered but was never coated with a film, sanding alone is usually all the preparation required.

The cost of sanding is material. Every pass removes wood that cannot be replaced, which matters on thin slats, veneered components and pieces that have already been restored several times.

What stripping is for

Chemical stripping dissolves and lifts a coating so it can be removed without abrading the wood underneath. It is the correct choice when there is a failing film finish, varnish or paint, particularly on profiles and mouldings a sander cannot reach cleanly.

Stripping does not level a surface or remove greying. It is almost always followed by sanding.

Choosing between them

A quick way to decide:

• Bare, weathered, no coating: sand
• Peeling varnish or paint: strip, then sand
• Carved detail or mouldings: strip to protect the profile
• Deep stains in bare wood: sand, and treat the stain
• Thin or previously over-sanded material: strip to preserve thickness

Why it matters on high-value pieces

Aggressive sanding of a set that has already been restored can round crisp edges, thin slats and expose fixings. On heirloom and custom pieces, the conservative route, strip where possible and sand only what must be levelled, is the one that keeps the furniture serviceable for another few decades.

Choosing between them

Stripping removes film finishes chemically; sanding removes wood. If there is varnish, lacquer or a failed film on the surface, strip first — sanding through a film drives fragments into the grain where they reappear as pale flecks under oil.

If the surface is bare, oxidised or oiled, sanding is the correct route and stripping adds nothing.

Getting the grit sequence right

Skipping grades is the most common cause of a blotchy finish. Each grade needs to remove the scratch pattern of the one before it, and those scratches are invisible until oil goes on and highlights them.

Stopping too coarse leaves a surface that drinks finish unevenly. Going too fine burnishes the wood closed so oil cannot penetrate at all. Consistency across the whole piece matters more than the exact number you finish at.

Safety and site control

Strippers need ventilation, gloves and eye protection, plus a plan for the residue — it should never be rinsed into planting or a pool. Sanding needs dust containment, because hardwood dust travels much further than people expect and is an irritant.

On a finished property, masking stone, glass, cable rail and planting before either process takes less time than cleaning them afterwards.

• Strip film finishes; sand bare or oiled wood
• Never skip more than one grade in the sequence
• Contain dust before the first abrasive pass
• Neutralise and dry fully before any finish goes on

When neither is the answer

Veneered and composite pieces cannot be sanded meaningfully; the skin is too thin. They are cleaned and coated only, and any attempt to sand them ends the piece.

Structural problems also sit outside both processes. Loose joints, corroded fixings and split slats need bench work before anything decorative is worth doing.

Common questions

How do I know if there is a film finish? Look for peeling, flaking or a glossy skin that lifts at the edges. Oiled wood wears away evenly instead.

Can I sand off varnish? You can, but you should not. Sanding drives film fragments into open grain where they show under any oil applied later.

What grit should I finish at? Fine enough to close the grain, coarse enough that it still absorbs. Consistency across the piece matters more than the exact number.