Exposed timber beams, rimu floors, pine shelving, and native hardwood joinery are some of the most beautiful features in a New Zealand home. Finishing them with the right varnish or oil protects the wood, brings out its natural grain, and keeps it looking great for years. Whether you're refreshing an old finish or starting fresh, this guide walks you through the process from prep to final coat.
Varnish vs Oil: Which Should You Choose?
Before you pick up a brush, it's worth understanding the difference between these two finishing approaches.
| Feature | Varnish (polyurethane/alkyd) | Penetrating Oil |
|---|---|---|
| Finish type | Surface film | Soaks into the wood |
| Durability | Very hard-wearing | Moderate; needs re-oiling |
| Repairability | Harder to spot-repair | Easy to re-coat locally |
| Look | Gloss, satin, or matt sheen | Natural, low-sheen |
| Best for | Floors, high-traffic surfaces | Beams, furniture, feature timber |
| Maintenance | Sand and recoat every few years | Re-oil every 1–3 years |
Varnish (typically water-based polyurethane or oil-based alkyd) forms a tough protective film on the surface. It's ideal for floors and surfaces that take a beating. Penetrating oils — such as Danish oil, tung oil, or hardwax oil — soak into the timber fibres, feeding the wood and leaving a more natural, matte appearance. Oils are popular for beams and feature timber where you want to preserve the raw, tactile feel of the wood.
What You'll Need
- Sandpaper (80–120 grit for initial prep, 180–240 grit for between coats)
- Sanding block or orbital sander
- Tack cloth or lint-free rags
- Quality natural-bristle or synthetic brush (check the product label — water-based products suit synthetic bristles)
- Timber cleaner or sugar soap (for previously finished surfaces)
- Your chosen varnish or oil — see product suggestions below
- Painter's tape and drop sheets
- Nitrile gloves and safety glasses
Step 1 – Prepare the Timber
Good preparation is the single most important step. Skipping it is the number-one reason finishes fail.
- Remove old finish: If the timber has a previous coat of varnish that is peeling or flaking, strip it back using a chemical stripper or by sanding. Always work with the grain.
- Clean the surface: Wipe down with sugar soap or a dedicated timber cleaner to remove grease, dust, and grime. Allow to dry completely.
- Sand smooth: Start with a coarser grit (around 100–120) to remove any roughness, then finish with 180–240 grit for a smooth surface. Always sand with the grain.
- Remove dust: Vacuum thoroughly, then wipe with a tack cloth. Any dust left on the surface will be trapped in your finish.
- Check moisture content: New or recently installed timber should be allowed to acclimatise and dry before finishing. BRANZ recommends timber reach equilibrium moisture content before coating.
Step 2 – Choose Your Product
NZ paint and finishing brands offer a solid range of interior timber products.
- Resene offers water-based polyurethane varnishes and timber stains suitable for beams and joinery.
- Wattyl has a well-regarded range of interior timber finishes including polyurethane and oil-based options.
- Dulux stocks interior varnishes and timber oils suited to NZ conditions.
- For hardwax oils and specialty penetrating finishes, check the ranges at Mitre 10 or Bunnings.
Always read the product data sheet for the specific number of coats, recoat times, and thinning instructions. Water-based products dry faster and have lower odour — a real advantage in NZ homes where ventilation can be limited in winter.
Step 3 – Apply the First Coat
- Stir, don't shake your varnish or oil to avoid bubbles.
- Apply a thin, even coat working with the grain. Avoid overloading the brush.
- For oils, apply generously, allow to penetrate for the time specified on the tin (often 15–30 minutes), then wipe off all excess with a clean lint-free cloth. Leaving excess oil on the surface causes a sticky, uneven finish.
- For varnish, use long, smooth strokes and maintain a wet edge to avoid lap marks.
- Allow to dry fully before the next coat — check the product label for minimum recoat times.
Step 4 – Sand Between Coats and Apply Further Coats
Once the first coat is dry, lightly sand with 240 grit to knock back any raised grain or dust nibs. Remove all dust with a tack cloth before applying the next coat. Most varnishes benefit from two to three coats for good protection. Oils typically need two coats, with the second applied after the first has cured.
Step 5 – Final Coat and Curing
Apply your final coat as smoothly as possible. Avoid working in direct sunlight or draughty conditions, which can cause the finish to dry too quickly and bubble. Allow the finish to fully cure before placing objects on surfaces or subjecting them to heavy use — curing can take several days to a couple of weeks even after the surface feels dry to the touch.
Safety Notes
Oil-soaked rags are a fire hazard. Linseed oil and some other drying oils can spontaneously combust if rags are bunched up. Spread used rags flat outside to dry completely, or submerge them in water in a metal container before disposal. Always work in a well-ventilated space, and check the WorkSafe NZ guidelines for safe use of solvents and finishes.
When to Call a Professional
While varnishing and oiling timber is well within the reach of a capable DIYer, there are times when it pays to bring in a qualified painter:
- Large or high beams — working at height safely requires proper scaffolding and experience.
- Native timbers (rimu, kauri, matai) — these can be tricky to finish correctly and are irreplaceable.
- Floors — floor sanding and finishing is a specialist skill; poor technique can permanently damage a floor.
- Lead paint concerns — older NZ homes may have lead-based undercoats on timber. If your home was built before the 1980s, consider getting it tested before sanding.
A professional painter will also have access to commercial-grade products and spray equipment that can deliver a superior result on large areas. You can find qualified local painters on tradedirectory.co.nz.