There are a number of different methods of repairing blemishes to timber surfaces.

We have them all here!

The method used depends upon the blemish, its location and the type of material that has been damaged.

Assessing the damage
Before choosing a method of repair, you need to assess the damage to the timber by looking carefully at the surface and the surrounding areas to see if any of the surface fibres have been fractured.

A fine, relatively deep crack across the fibres means that the timber has been fractured. These cracks need to be filled. Small dents and scratches in unfractured timber can often be simply steamed out or sanded back.

Rust stains on timber surfaces can be removed by brushing the stain with oxalic acid, and bubbles in veneered timber can be smoothed out by slicing the veneer surface and gluing the area down.

Small scratches and dents
To remove a dent from an unfinished solid timber surface, place a wet rag over the damaged area and press a hot iron down against the rag. Make sure that the rag covers the entire area of the dent. Wait a few seconds, then remove the iron and the cloth. Let the area dry then check it to see if the dent has been removed. You may need to apply the wet rag and iron a few times to remove the entire dent. The iron's steam penetrates the compressed surface fibres of the timber, causing them to swell back to their original state, removing the dent. When the dent has been removed, sand the surface of the timber.

Dents in veneered particle board can be steamed out in the same way. However, the veneer is only about 1mm thick, so be careful when sanding not to expose the particleboard substrate below.

Dents and bruises can also simply be sanded out using abrasive paper or scraped flat using a cabinet scraper. You should take care, however, not to sand only around the immediate area of the dent. This will cause a deeper indentation which is often more noticeable on a flat surface than a little filler. When sanding, rub the abrasive paper or the scraper over a broad area and don't be tempted to use the heel or the toe of a sanding machine. Always sand or scrape timber in the same direction as the grain.

An option for unfinished timbers is to place a small amount of methylated spirits over the area to be raised. Allow the methylated spirits a few moments to soak into the timber, then set the methylated spirits alight. Be careful, however, when using this method of repair. In particular, do not use too much methylated spirits, as this can scorch the surface and you will then have to sand the scorch mark out.

Small dents in a piece with a modern lacquered finish
It is very difficult to remove a dent in a timber surface with a modern lacquered finish without damaging the surface finish. There is, however, one method you can try. If the surface finish is intact, make pin holes through the lacquer into the timber, then apply a damp rag to the surface and press the rag gently with a warm iron for short periods. Make sure the iron is not too hot; it should be set on low to medium heat. Use cotton cloth and do not apply undue pressure to the cloth with the iron.

A few white patches may form under the lacquer as a result of using this technique. These can be removed quite easily by wiping with a cloth dampened with a mixture composed of equal parts of lacquer thinner and turpentine.

Fractures
When a dent or hole is too deep or large to steam out and the surrounding timber has been fractured the area should be filled. There are a number of products that can be used.

Wood putty
The first product is wood putty. There are two sorts: water-based and turpentine-based. Both of these types are available in a range of popular timber colours.
The advantage of using waterbased putty is that it can be coloured to match a timber's hue with the use of powdered pigments. These are available from shops that stock French polishing products. Coloured pigments can be added to wet putty or mixed with water and painted onto dry putty. pigments of different colours can be mixed together to create a close colour match.

Before applying putty, make sure the hole or dent that you want to fill is free from dust. Use a putty knife or a similar object to push the putty well into the hole.
If the hole is shallow, use a pin to make a number of small holes in the dent to help anchor the putty in the hole. Fill the hole to above the level of the surface. Allow the putty plenty of time to dry then sand the putty back to the level of the surface. You may need to apply a second layer of the putty, as certain brands have a tendency to sink a little as they dry.

If you intend to add coloured pigments, start by using a light base colour and adding darker colours a little at a time until you get the right hue. Bear in mind that the colour of the wet putty will closely match the colour of the filler after a clear finish is applied.
Turpentine-based wood fillers can be tinted by adding a little oil based stain. Use an eye dropper and add the stain one drop at a time, as the colour tends to be quite strong.

Plastic fillers
For dents that cannot be tilled with standard timber putty, you can use a plastic filler. This usually comes as a two-part mixture, one part filler and the other hardener.

Plastic fillers set hard and can generally be filed, drilled and screwed, so they are useful for filling large holes, such as holes left by knots. Plastic filler is also the best filler for a bruise on a sharp edge.

Read the manufacturer's instructions before mixing and only mix up the amount you need for the job. The dent should be filled and left to dry before you sand or file it flush with the surface.

Plastic fillers can be coloured using either pigments or stains. Add the colouring before adding the hardener.

As plastic fillers do not soak up stain after they have set, colouring them later can be difficult. It's best to get the colour right while the filler is wet. In view of this, use a filler that has a white hardener. If you intend to use a car body filler, check the hardener, as most types have a coloured hardener.

Wax fillers
Wax fillers are available in stick form in a range of timber colours suitable for most repairs. They can be used on scratches and dents in both finished and unfinished surfaces and are extremely useful on pre-finished melamine boards, as they can be polished over and touched up after finishing and also can be blended with powdered pigments to create many different shades of colour.

To blend a wax stick with a powdered pigment, put the wax stick in a jar and put the jar inside a saucepan filled with water. Place the saucepan on the stove and bring the water to the boil to melt the wax. Add the powdered pigment, stir until thoroughly blended and allow the mixture to cool.

To apply the wax, rub it over the damaged area until a coating has been applied. With a clean putty knife, remove the excess.

Give the area a final finish with an appropriate abrasive. Use 180 to 320 grit paper for bare timber or 0000 grade steel wool for polished timber surfaces.

Alternatively, use the blade of a putty knife that has been warmed by your hand to push the wax into the hole or scratch. This method has the advantage of being the least messy and doesn't leave as much residue.

You could also melt a couple of drops of wax into the dent or scratch using a flame. However, the carbon residue from the flame has a tendency to mix with the wax and darken its colour.

Removing rust stains
Equipment: 20g oxalic acid, water, abrasive paper (fine grade) and a pencil brush.

Rust marks, which are generally caused by ageing nails and screws, can be removed from timber surfaces by applying a solution of oxalic acid and water. Oxalic acid can be ordered from specialty furniture supply shops, pharmacies and some hardware stores.
A few grams of oxalic acid is generally all that is needed for each job. Be sparing with the acid, as it tends to bleach timber. If light bleach patches appear on the timber surface, disguise them by applying a mild solution of the acid to the entire timber surface.

Here's how
1. Mix approximately 20 g of oxalic acid in about 100 ml of water. This will generally be enough to remove rust stains from a number of pieces of furniture.

2. Apply the mixture to each stain with a pencil brush and then allow to dry. When the mixture on each stain is dry, brush away the remaining acid crystals and sand each spot carefully with a fine-grade abrasive paper.

3. If the rust stain has not disappeared, repeat the procedure a second time. A maximum of three attempts should see it eliminated.

Repairing bubbled veneers
Veneer that has lifted, causing bubbles under the surface, is common on old pieces. Bubbled veneer can be fixed easily and with little equipment. Either of two techniques can be used to fix the problem, depending on the sort of adhesive that has been used to glue down the veneer.

Veneer glued down with PVA adhesive
Equipment: PVA adhesive, rag, block of scrap timber, utility knife or craft blade, large-needled syringe, quick-action cramp or heavy object.

Here's how
1. With a utility knife, make a slit along the grain of the wood right across the bubble.

2. Fill a syringe with a large needle with PVA adhesive and slowly inject the adhesive into the slit in the bubble. Press the bubbled veneer down carefully with your fingers and remove the excess adhesive with a wet rag.

3. Place paper over the surface of the veneer. Put a block of scrap wood on top of the paper and then put pressure on the veneer surface by using a quick-action cramp. Alternatively, place a heavy object, such as a large telephone book, on the block.

Veneer glued down with animal adhesive
Animal adhesive was often used to glue down veneer on furniture constructed in the eighteenth and nineteenth centuries. To repair bubbled veneer glued with this type of adhesive, use the technique below.

Equipment: Kitchen tongs, quick-action cramp, block of medium density fibreboard.

Here's how
1. Clean the finish from the surface of the area to be repaired.

2. Heat a block of medium density fibreboard (MDF) in a microwave or in a conventional oven to between very warm and hot. Undertake this carefully so that you do not set the block of MDF on fire.

3. Place the block in position over the bubble using kitchen tongs. Cramp the block down using a quick-release cramp, to put pressure on the surface.

4. Leave the cramp fixed in position until the block of MDF has cooled completely. The block's heat will cause the old adhesive to melt, and the adhesive will harden and re-grip the veneer as it cools.

Source: Repairing Furniture (Murdoch Books)