Wood Filler vs Wood Putty: Which Should You Use?
Filler hardens, sands and takes a finish. Putty stays pliable and is meant for finishing touch-ups after coating. Using them the wrong way round is the most common cause of a repair that shows through the topcoat.
Updated · Confirm product suitability before full application
1. Quick comparison
| Factor | Wood filler | Wood putty |
|---|---|---|
| Cures hard | Yes; dries to a sandable solid | No; stays flexible |
| Sandable | Yes, flush with the surrounding surface | Not meaningfully |
| When applied | Before sanding and finishing | After the finish is on |
| Takes stain | Variably; usually lighter or darker than wood | Pre-tinted to match the finished colour |
| Shrinkage | Some, on deeper fills; may need a second pass | Minimal |
| Structural contribution | Some, on small defects | None |
| Best for | Grain, gouges, joints, open defects | Nail holes and blemishes in finished work |
2. How each behaves as it cures
Wood filler sets into a hard mass that can be sanded flush and shaped. Deeper fills usually shrink slightly as solvent or water leaves, so a repair much over a few millimetres deep is better built in layers than in one pass. Each layer should be allowed to cure before the next.
Putty does not harden in the same way. It is designed to be pressed into a small void and wiped flush, remaining pliable so it tolerates the slight seasonal movement of finished timber without cracking out. That flexibility is exactly why it cannot be sanded or used as a base for a finish.
3. Stain and topcoat acceptance
Filled areas rarely absorb stain the way surrounding timber does, because the filler has no grain structure. A repair that looks invisible on bare wood can turn into a pale or dark patch the moment stain is applied. This is the single most common complaint about wood filler, and it is a testing problem rather than a product fault.
Test the filler, stain and topcoat together on an offcut of the same timber before committing. Where an exact match matters, consider tinting the filler, or plan the repair so it falls where a solid-colour finish will cover it.
- Always test on an offcut: same timber, same filler, same stain, same topcoat.
- Sand the repair and surrounding area evenly: uneven sanding changes stain uptake on its own.
- Remove all dust before staining: filler dust in open grain reads as a haze.
- Consider a pre-stain conditioner: it evens absorption across the repair boundary.
- Match putty to the finished colour, not the raw timber: putty goes on last.
4. Joint movement changes the answer
A joint that opens and closes with humidity will crack any rigid fill placed in it. Before filling, work out whether the gap is a static defect or a moving joint. Static defects — a gouge, a knot hole, an open grain pocket — take filler well. Moving joints need either a flexible sealant or a mechanical solution such as a fillet strip.
Corner joints on furniture, panel-to-frame gaps and anything spanning two pieces of timber with different grain direction should be treated as potentially moving until proven otherwise.
5. Choosing by repair type
| Repair | Use | Notes |
|---|---|---|
| Open grain before finishing | Filler or grain filler | Sand flush; test stain acceptance |
| Gouge or dent in bare timber | Filler, built in layers if deep | Allow each layer to cure |
| Knot hole | Filler; consider a bonding product for depth | May need two passes for shrinkage |
| Nail hole in finished work | Putty, colour-matched | Applied after the topcoat |
| Moving joint or corner gap | Flexible sealant, not filler | Rigid fill will crack out |
| Structural gap or split | Mechanical repair plus adhesive | Filler is not a structural product |
6. Common mistakes
- One deep fill instead of layers: shrinkage leaves a dished repair.
- Staining without a test: the repair boundary becomes visible only after it is too late.
- Filler in a moving joint: it will crack in the same place within a season.
- Putty before the finish: the topcoat will not sit correctly over pliable material.
- Sanding only the repair: creates a halo of differently prepared surface around it.
Frequently asked questions
Can I stain over wood filler?
You can, but filler rarely absorbs stain identically to timber. Test the full sequence on an offcut before applying it to the workpiece.
Is wood putty sandable?
Not meaningfully. Putty stays pliable by design and is intended to be pressed in and wiped flush after finishing, not sanded.
What should I use for a gap that keeps reopening?
A gap that has already cracked a rigid fill is moving. Use a flexible sealant or a mechanical repair rather than filler.