How To Fill Large Holes & Gaps in Wood

Wood Filling Explained

Being a natural substrate, wood is particularly prone to cracks opening on its surface, which is why wood fillers have been developed by a range of decorating and woodworking manufacturers. These wood fillers consist of either a composition of wood by-products such as wood dust combined with other binders or are made of completely synthetic materials that mimic wood. More often not, wood fillers are designed to accept paints and stains that are designed for wood, allowing a surface to be repaired so it is blemish free.

There are a number of occasions in which wood filler may be needed:

• To repair nail holes
• To repair badly worn wooden flooring
• To repair chipped wooden furnishings such as tables, bannisters & skirting boards
• To repair large gaps caused by rotting wood, such as window frames

The Best Wood Filler

Finding the best wood filler to use is a crucial step in the process of repairing interior or exterior wood. When choosing a wood filler there are a number of things to consider, including whether you want it ready-mixed, what you are using it for, the colour you want and whether it can be used on interior or exterior wood.

A range of wood fillers that we believe provides everything you need when it comes to wood filler is from Toupret. Having the flexibility to apply filler how best suits you is crucial. That is why we love that the Toupret wood filler range has a number of products to suit both DIY'ers and professional decorators. They have a ready-mixed, easy to apply Toupret Wood Filler that comes in a small tube for easy application, plus a larger Ready Mixed Wood Filler or Powdered Wood Repair Filler that both provide the flexibility to either have a ready to apply filler from the tub, or the ability to mix it to your desired consistency. They also do a Toupret Wood Hardener that is recommended to be applied to the filler for optimal results and an ultra-hard finish even on damp wood.

Our recommendation for the best wood filler is the Toupret Extrem Wood Filler, also from Toupret's filler range, as it provides a comprehensive repair system for interior and exterior wood, plus it is designed to repair both large and small gaps, cracks and holes. What makes it such an effective wood filler is that it has excellent adhesion, strength, water resistance and flexibility, which are all crucial, especially when filling exterior timber. Unlike other fillers, it has no limitation to the depth of application, meaning it can fill large holes just as effectively as small holes. This is perfect if you have missing chunks of wood as you can reconstitute the missing parts.

Overall, it offers everything you could want from a wood filler and will ensure that you achieve the hgihest-possible standards when repairing any wooden surface.

How To Fill Large Holes & Gaps Using Wood Filler

The process of filling wood is relatively easy & quick if you have the right tools for the job. For this you will need a few things:

• Dust sheet
• Wood filler
• 120 grit sandpaper
• 180 grit sandpaper
• Cloth
• Filling knife

The key when filling a surface is to take your time. The more precise you are, the less mess you will make and the easier the process will be. If you take your time, you will get completely smooth surface where you once had a large gap.

Step 1 - Prep the surface

The first stage of any decorating project is preparation. Ensuring the surface is clean before you start anything, whether filling interior or exterior wood, is crucial to ensure the best possible results. Remove any loose wood or any failing wood treatment such as peeling paint. Once this is done, clean down the surface of any large bits of dirt and grime using a cloth, or if there are large amounts of dirt and loose material on exterior wood for example. Use a light key (120 grit) sandpaper to remove this.

Step 2 - Applying the wood filler

If you have opted for a powdered wood filler, mix this to your satisfied consistency or follow the manufacturers instructions. Once you have some wood filler on your filling knife, work the filler into the gap or hole, working the filler from one side to the other. Sometimes it is easier to use your finger to push the filler into a crack where there is a right angle. While it is often recommended that you overfill the hole using the wood filler to ensure a compact build up, this isn't always necessary. If you have sufficiently filled the hole, simply skim off any excess using the filling knife at this point as it will save you time when it comes to sanding. This can also be done with a wet cloth to remove the filler while it is wet.

Step 3 - Allow the wood filler to dry

All wood fillers have different drying times, which is why you should check the manufacturer instructions to see what they recommend. It is important to remember that the more filler you have applied, the longer the drying time. It is better to be safe than sorry if you are unsure, as wet filler is not going to sand down smoothly.

Step 4 - Sand the filler down

Start sanding down the area using a 120 grit sandpaper to remove the bulk of the filler, then moving to a fine 180 grit paper to achieve a smooth finish. If you want to match the appearance of the filler to the wood, move the sandpaper in the direction of the grain to leave a slightly scratch that replicates the wood.

Step 5 - Apply your wood finish

The chances are that if you are repairing woodwork, you are looking to finish it to complete the look. This can be done using a wood paint, wood stain or a wood varnish, depending on the look you want.

• Wood varnish - a varnish remains on the outside of wood, forming a protective and usually clear barrier on the wood
• Wood stain - Stains penetrate the wood, allowing the natural grain of the wood to be seen through the treatment, often available in a range of colours
• Wood paint - refers to opaque solid clear finishes, which completely cover the grain of the wood

When it comes to wood finishes, no matter what finish you want to achieve, there are a range of excellent products available. Due to the colour difference between the filler and the wood, it is recommended not to use a clear varnish and instead opt to paint or stain the wood and filler.

In terms of a wood paint for interior wood, then this depends on your preference for finish. These products are available in matt, eggshell, satin and gloss finishes, that all vary in their level of 'sheen', also known as their ability to reflect light. The most popular form of finish for interior woodwork is a satin finish, in which case we would recommend Dulux Trade Satinwood. Although is a water-based formulation, it dries like an oil-based satin wood paint. It has exceptional durability and can be mixed in any colour you choose, making it brilliantly versatile for any interior woodwork.

For an exterior wood paint, we would highly recommend Sadolin Superdec. It is an exterior wood paint that can be mixed in almost any colour, meaning that not only will your wood be protected from further damage, but you can transform it in any way you want. The options are endless!

If you want a slightly more subtle coloured wood finish, then Sadolin Classic is a hugely popular choice. It again can be mixed in a huge array of colours and offers excellent protection to interior & exterior wood.

Frequently Asked Questions

Q. Is wood filler stainable?

Yes, wood filler can be stained, but it is slightly riskier than painting it. Stains unlike paints absorb into the wood, creating a problem due to the fact that the filler is not as porous as the wood, resulting in the wood filler spots appearing a different colour. There are a number of ways to minimise this. Firstly, try and sand the full surface once filled to ensure that the wood and filler have been sanded to the same texture. Another way to reduce this is to buy a dry filler and add your stain to it to provide a similar colour. If you are unsure, test the filler once stained against the surface you a filling to gain an idea of the difference.

Q. Is wood filler waterproof?

Wood fillers designed for exterior use once they are fully dried provide a hardwearing, waterproof finish. The Toupret Extrem Wood Filler for example is completely water resistant.

Q. Can wood filler be painted?

Wood filler is ideal for painting as due to the way a paint creates a film on the surface of a material, you will not be able to see where the filler has been applied.

Q. How much is wood filler?

Wood filler can vary in price due to the quality and longevity of the product. While you can get wood fillers for a couple of pounds at large DIY shops, we wouldn't recommend using these as you get what you pay for. You can get a high-quality filler in a small tube for under £5, while you can get a large pack of good-quality would filler for under £10.

We hope this has answered any questions you may have had regarding how to fill large holes & gaps in wood, plus what the best wood fillers to use are. Shop our range of paint, painting tools & decorating supplies we have in stock here at Painters World, all with FREE next working day delivery available.