Best Primer for Varnished Wood: 2025 Expert Review
DR Joinery
Expert Joiner & Bespoke Staircase Specialist
Painting over varnished wood is one of the most common DIY requests I hear about, especially regarding staircases. Dark, orange-varnished pine banisters are a staple in many of York's older properties, and modernising them with paint can transform a hallway. However, it's also where many homeowners come unstuck.
The problem is adhesion. Varnish is designed to repel moisture and dirt, which means it also repels paint. If you use a standard emulsion or cheap undercoat without proper preparation, a simple knock with a vacuum cleaner will chip the paint right off, revealing the brown varnish underneath.
In this review, I've selected three primers I encounter often. Whether you need a small pot for a quick touch-up, a trade-quality tub for a full staircase renovation, or a specific solution for mixed-material repairs, here is my professional take on what works.
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Specs vs. The Real World
The Spec: "'No Sanding Required' Claims"
"Many modern primers claim you can paint directly over varnish without abrasion."
In my 20 years of experience, this is a risk not worth taking on high-traffic areas like handrails. Always give varnished wood a 'key' with fine-grit sandpaper/abrasive pad first. It creates microscopic scratches for the primer to grip.
The Spec: "One Coat Coverage"
"The tin says it covers dark colours in one coat."
Dark varnish (especially the mahogany stain common in 1980s York homes) often bleeds through. Plan for two thin coats of primer rather than one thick gloopy one. It cures harder and looks better.
My Top 3 Recommendations
Three options to cover different needs and budgets
RUSTINS White Primer/Undercoat 250ml
RUSTINS
This 250ml tin is perfect for small jobs or touch-ups on existing paintwork. Whilst the price per litre is higher, the low entry cost makes it the ideal budget choice if you only need to prime a few spindles or a section of skirting.
The Good
- Fast drying (touch dry quickly)
- Low odour (good for occupied homes)
- Combines primer and undercoat in one
The Bad
- Expensive if buying large quantities (buy a 2.5L tin for big jobs)
- Small tin size not suitable for a full staircase
Installer Tip:
Don't overload your brush despite the 'high coverage' claim. On varnished wood, two thin coats stick better than one thick one. Ensure the varnish is clean and free of furniture wax before applying, or it will react.
Priced at £7.59 at the time of writing
Check Price on AmazonJohnstone's - Quick Dry Gloss Primer Undercoat - 2.5 L
Johnstone's
Johnstone's is a brand we see on professional sites daily. This 2.5L tin offers excellent value and is the correct choice for painting an entire staircase. The water-based formula means it won't yellow over time, and it dries fast enough to get two coats done in a day.
The Good
- Excellent opacity (hides dark varnish well)
- Water-based: brushes wash out in water
- Large coverage area ideal for full staircases
The Bad
- Requires good surface preparation (sanding) for maximum adhesion on varnish
- Can dry too fast in hot weather/direct sunlight
Installer Tip:
When painting a full staircase, tackling the spindles can be tedious. This paint flows well, but watch for runs in the corners of the mouldings. I find a synthetic brush works best with this water-based formula to avoid brush marks.
Priced at £19.60 at the time of writing
Check Price on AmazonRUSTINS Quick Drying MDF White Primer 500ml
RUSTINS
Why MDF primer in a varnished wood list? Staircase renovations often involve replacing damaged risers or boxing in pipes with MDF while keeping the original varnished strings. This primer is essential for those new additions, ensuring the texture matches your painted woodwork perfectly.
The Good
- Seals the 'furry' edges of cut MDF effectively
- Prevents different absorption rates between new MDF and old wood
- Dries very quickly
The Bad
- Specific use case (mainly for the new MDF parts)
- Price per litre is higher than general purpose primer
Installer Tip:
If you are replacing your stair risers with MDF and painting them to match the stringer, apply this specifically to the cut edges of the MDF. It stops the paint sinking in. Once primed, you can use the same topcoat across both the primed MDF and the primed varnished wood for a seamless look.
Priced at £11.49 at the time of writing
Check Price on AmazonFrequently Asked Questions
Can I paint straight over varnished wood without sanding?
What happens if I use ordinary emulsion on varnished wood?
Is water-based or oil-based primer better for varnished wood?
How do I stop brown stains bleeding through the white paint?
Should I replace or paint my varnished staircase?
Do you offer staircase renovation services in York?
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