Best Two Part Wood Filler for Restoration: 2025 Expert Review
DR Joinery
Expert Joiner & Restoration Specialist
If you own a period property, you'll arguably know the sinking feeling of finding soft, spongy timber on a window sill or door frame. The instinct is often to replace the joinery entirely, but with the right two-part wood filler, many 'ruined' timbers can be saved.
Here in York, we deal with Victorian terraces where moisture is a constant battle. Standard one-part fillers shrink and crack within months. A high-quality two-part system—utilising a resin and a hardener—chemically cures to become harder than the wood itself, bonding permanently and resisting moisture.
In this guide, I'll walk you through three two-part fillers I keep in the van. Whether you're patching a small crack or reforming a rotted corner on a sash window, these are the products that will ensure your paintwork looks pristine and your joinery stays sound.
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Specs vs. The Real World
The Spec: "Sandable in 20-30 Minutes"
"You can fill, sand, and paint in a single hour."
In a cold Yorkshire garage or on a damp site, curing takes longer. Conversely, on a hot day, it sets rock hard in 10 minutes. If you wait too long to surface it, you'll struggle to sand it flush without damaging the softer surrounding timber.
The Spec: "Stainable"
"The filler accepts wood stain to match the original timber."
Two-part fillers are essentially plastic resins. Whilst they claim to take stain, they rarely absorb it like natural grain does. They are best reserved for painted joinery. If you must stain, use a coloured filler close to your timber shade first.
My Top 3 Recommendations
Three options to cover different needs and budgets
Tetrion TWF600/TWF606 Woodfil 600g Flexible Wood Filler Natural Ready Mixed
Tetrion
This is a solid entry-level two-part filler ideal for smaller jobs where you don't need a massive tub. Despite the confusing 'Ready Mixed' label in some listings, this is a proper two-part system that offers reliable durability for general repairs without breaking the bank.
The Good
- Very affordable for small repairs
- Simple mix ratio reduces intimidation for novices
- Flexible composition helps prevent cracking with wood movement
The Bad
- Small quantity not suitable for major rot repairs
- Finish can be slightly coarser than premium brands
Installer Tip:
Mix small golf-ball-sized batches. This product goes off quickly, and there's nothing worse than a trowel full of rock-hard filler you have to throw away. Apply it proud of the surface, as it doesn't shrink, then sand back.
Priced at £7.33 at the time of writing
Check Price on AmazonTetrion Powerfil 2 Part Professional Multi-Surface Filler, 2 kg
Tetrion
When I'm dealing with extensive rot on a sash window sill, I need bulk and strength. Powerfil comes in a 2kg tub, making it perfect for those deeper cavities. It sets incredibly hard, allowing for drilling and screwing, which is essential if you're reforming structural sections of a frame.
The Good
- Cost-effective for large restoration projects
- Sets extremely hard – can anchor screws
- Versatile – adheres to masonry and metal too
The Bad
- Can be difficult to sand by hand if left to cure too long (use a power sander)
- Greyish colour might require extra primer coats if painting white
Installer Tip:
If you are filling a deep hole (over 20mm), drive a few stainless steel screws into the solid timber at the base of the cavity first. This acts as a 'key' or rebar for the filler to grip onto, ensuring the repair never falls out.
Priced at £22.52 at the time of writing
Check Price on AmazonEverbuild 2-Part High Performance Wood Filler – Fast Drying – Weatherproof – Easy to Mix and Apply – White – 500g
Everbuild
Everbuild is a brand found in almost every joiner's van for a reason. This filler is exceptionally good at holding a sharp edge, making it the best choice for reforming corners on casements or sash details. It's also fully weatherproof, which is non-negotiable for York's wet winters.
The Good
- Excellent edge retention for modelling corners
- High temperature and weather resistance
- Fast drying (30 mins to paint)
The Bad
- Strong styrene odour during application (use in ventilated areas)
- Hardener tube can be fiddly to squeeze completely empty
Installer Tip:
To get a sharp corner without endless sanding, shape the filler roughly with a filling knife, then cover it with a piece of stiff acetate or plastic packaging tape. Smooth it out through the plastic. Once cured, peel the plastic off for a glass-smooth, perfectly shaped corner.
Priced at £12.60 at the time of writing
Check Price on AmazonFrequently Asked Questions
Why use two-part filler instead of ready-mixed?
Can I screw into two-part wood filler?
How do I prepare rotten wood before filling?
How much hardener should I add?
When should I call a professional joiner?
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