Repairing a scratch in wood It almost always requires less than you imagine. The problem is that you start with the most aggressive remedy, and end up with an area even more damaged than before.
The rule is one: understand first how deep is it, then choose.
Nail test: three cases
Run your nail perpendicular to the scratch.
- It doesn't hook up: the sign is only in the finish. Level 1.
- It hooks slightlyThe finish is engraved and the wood may have been slightly scratched. Level 2.
- Get into the groove: the wood is engraved. Level 3.
Everyone has a different remedy, and getting the level wrong means working in vain.
Level 1: Finishing only
On an oiled or waxed surface, simply reapply the product: a little oil on a cloth, passed in the direction of the grain, and the mark disappears because it was only an optical interruption.
Furniture polish or, with caution, a very fine abrasive paste works well on paint. Always rub in the direction of the grain, never in circles: circular movements leave a dull appearance that can be seen when held up to the light.
The walnut remedy exists and is true: rubbing the pulp of a walnut kernel on the superficial scratch leaves oils and pigments that camouflage it. It lasts a few weeks, then needs to be repeated.
Level 2: The finish is open
Here you need to fill in.
- Clean up the area with a slightly damp cloth and let it dry.
- Hard touch-up wax of the closest color: heat it slightly, press it into the groove, remove the excess with a plastic edge.
- Lucida with a soft cloth.
The advice that makes the difference is on the color: if you have two shades and neither is exact, choose the clearest one. A lighter touch-up of the wood is much less noticeable than a darker one, because the eye perceives the darkness as a shadow, that is, as a deep defect.
Level 3: The wood is engraved
When the groove is in the wood, the local retouching is always visible. There are two ways.
- Sand the entire surface with progressive grits and redo the finish. On an oiled surface, it's a one-hour job and easily within anyone's reach.
- Lift the fiber with steam, If the mark is a dent and not a cut: apply a damp cotton cloth to the area and iron for a few seconds. The crushed fibers will swell and rise. It works surprisingly well on unpainted wood, but it won't work if the fibers have been cut.
When is it best to stop?
There is one case in which the best remedy is none: when the signs are numerous and distributed.
A floor that's been used for years has a patina that's the result of thousands of tiny marks. Repairing one makes it more visible, not less: it creates a new area in the middle of a worn surface.
On those plans the right job is restore oil to the entire surface, once or twice a year. The marks remain, but they all return to the same tone, and the piano once again has the appearance of a cared for object rather than a worn one.
Wood, unlike almost any other material, has this privilege: it can always be repaired, and each repair leaves it usable for another ten years.
Sources
- CATAS: scratch resistance tests of finished surfaces (UNI EN 15186)
- FederlegnoArredo: Best practices for maintaining and refinishing wooden furniture
- Central Institute for Restoration: principles of reversibility and minimal intervention in restoration of wooden artefacts
For antique or valuable furniture, consult a restorer before any intervention: an incorrect touch-up reduces the value more than the defect.