The Fine Art of Sanding - Wood Floor Sanding Guide Part 1

You’re the proud owner of a beautiful wooden floor, whether it’s a gorgeous old parquet masterpiece or something contemporary, perhaps in glorious solid oak.

The great thing about wood floors is that you can sand them down when they get scuffed, stained and grubby, bringing the beauty of the grain and the depth of colour back to life so they look brand new.

If that sounds appealing, it’s time to get sanding. Here’s our simple guide to sanding, finishing and maintaining a wooden floor. But first, a quick word about letting it lie. If you prefer, you can always leave your wood floor to slowly build up a gorgeous, battered patina. While sanding and refinishing deliver a sleek, beautiful, new-looking appearance, there’s no reason why you can’t leave your floor to do its own thing and wear naturally. It’s a style thing.

Why sand and renovate your floor?

Newly laid floors are sanded to make them 100% level, and old floors are sanded to get rid of old, tatty wood finishes and level out worn areas. If you want to apply a finish to your floor, it will always have to be sanded and prepared first.

Wood floor sanding, finishing and maintenance

You’ve decided you want to renovate your old wooden floor or give your newly laid floor a beautiful, durable finish. In our two-part guide, we’ll reveal how to tackle sanding, preparation and the application of lacquers and oils, as well as aftercare and maintenance.

Step 1 – Sanding and preparation

Before you start sanding back to the bare timber, you need to remove or countersink any screw or nail heads that protrude. The sanding itself takes several stages, depending on the floor’s overall condition, and there are a few important things to take into consideration:

1. Is the floor solid or engineered? If your floor has already been sanded, can it take any more? You might need to remove a section of the door threshold or skirting board to find out.
2. Which sanding belt or sanding disc grit should you use? This depends on the condition of the floor. If it’s badly worn and uneven, start with coarse sandpaper, followed by successively finer papers. Sandpaper for wooden flooring generally ranges from 16 to 150 grit, with 16 being the most aggressive and 150 the finest. Find a full range of sandpaper and sanding abrasives here.

Most sanding jobs start with around 36- or 40-grit sandpaper, working up to around 120 grit for the final sand. If you or your contractor aren’t using a dust-free sanding machine, remember to remove all the dust with a vacuum cleaner between changes of sandpaper grade. If possible, save some of the fine sanding dust. You’ll need the finest stuff later if your floor needs filling.

Start in the middle of the room and work your way to the edges. Guide the sanding machine carefully around the floor at a moderate, steady speed. Remember that leaving the machine in one spot for too long can create gouges that are difficult to even out.

What about the grain? It’s always best to sand with the grain rather than against it. Sanding against it can leave you with a slightly furry finish because you’re disturbing the grain instead of going with the flow. If it isn’t possible to follow the grain because of the way the pattern is laid, there’s a way to overcome it:

• For floors with a complex herringbone pattern, sand in the same direction as the light source.
• For parquet flooring, sand at a 45-degree angle to the pattern.

Once the central area of the floor has been sanded, it’s time to tackle the edges. This is where edge sanding comes in, removing old finish from the room’s perimeter where the belt or drum sanding machine won’t reach. Kick off with 36- or 40-grit paper, then work your way up to the finest.

It’s best to work in gentle, slow circular movements, working your way steadily through the grits from coarse to fine. If you miss out grit levels, you could end up with a strange-looking halo effect, which shows up even more when you apply the wood finish.

Merv, our resident sanding expert, says, “When sanding herringbone or Parquet flooring, it’s always important to sand in the direction of one set of the blocks, usually 45 degrees to the room. Be sure to apply the lacquer in the same direction, this will help prevent demarcation lines (sanding marks) in the final finish.”

Sanding direction

Step 2 – Mixing and filling

You should have plenty of fine sanding dust left over from using 80–100 grit sandpaper. It’s exactly the right colour to match the floor, so mix it with a clear wood filler gel such as Bona Mix and Fill or Osmo Wood Reviver Power Gel. Use it to fill any small holes or gaps up to 6 mm between the planks or parquet tiles. If you have bigger gaps, fill them with a one- or two-pack wood filler instead.

Step 3 – Final sanding and preparation

You need to carry out a series of final sands to smooth your repairs and make the surface finish-friendly. Use a circular motion and bring 100 grit into play, followed by finer 120 or 150 grit grades. Remove all the dust between stages, as residue from the rougher papers can catch under the sander and leave nasty scratches.

Parquet floors made from tropical hardwoods such as teak, mahogany, walnut and other naturally oily hardwoods may need to be scrubbed with methylated spirit after sanding and before varnishing. This is to remove any natural oils from the freshly sanded surface of the wood that might otherwise cause adhesion issues with the varnish. Another precautionary step is to use a primer formulated to work better with oily hardwoods, such as Bona Intense Primer or Manns Trade Intense Primer. If the floor is to be stained, apply the primer once the wood stain has fully dried and the surface has been denibbed.

Step 4 – Applying wood finishes to floors

When it comes to choosing wooden floor finishes and treatments, there’s a wide range of options to suit everyone’s style and needs. If you’re lacking inspiration and need help, Pinterest can be a great place to start looking and get those creative juices flowing.

Staining

• Products like Morrells Light Fast Solvent Wood Stains are great for delivering beautiful wood grain definition and excellent overall colour. Because they’re spirit-based and dry pretty fast, it’s best to apply them to only one small area at a time to avoid patches. Take it easy and you should be fine.
• Apply your stain with a brush, rag or special mohair pad. Get rid of any excess with a clean, dry cloth to help the final lacquer finish stick properly.
• Never use an exterior wood stain designed for decking, fencing or garden furniture, since these stains contain water repellents that also repel water-based floor lacquers.

Sealing

• Always choose a water-based floor finish that includes a primer or sealer designed to enhance the wood’s natural colour and reduce the risk of ‘side bonding’, where the planks or parquet tiles get stuck together. If the wood shrinks, which it often does because of atmospheric conditions, central heating and seasonal temperature changes, the lacquer film gluing the wood together cracks, which looks awful.
• Apply your sealer with a T-bar applicator or a short-pile mohair roller. Apply the sealer thinly and evenly. Be gentle and let the roller do the job it’s designed for without putting pressure on it.
• When the sealer is completely dry, which usually takes between two and four hours, you can apply your first layer of water-based top coat. You don’t need to do any more sanding.

Lacquering

Did you know that varnish and lacquer are the same thing? People in the trade tend to refer to varnishes as lacquers, while the public more commonly refer to these products as varnishes.

• Again, use a T-bar applicator or a short-pile microfibre roller to spread the product evenly over the floor. Let the roller do its job without applying downward pressure. If you press down, you can form annoying pools of excess lacquer.
• Leave it to dry completely for 2–3 hours, then sand the lacquer with a rotary sanding machine and a 150/180 mesh screen. This is often called denibbing.
• Clean off all the dust and debris, and you’re ready to apply the top coat.

Top coat

• Do you use a single-pack varnish, such as Manns Extra Tough Floor Varnish, or a two-pack lacquer system, such as Manns Trade Extra Tough Pro Lacquer? And do you choose a matt, semi-matt, satin or gloss finish? As a rule, your lounge, bedroom and so on are best given a coat of something like Manns Extra Tough Floor Varnish or Bona Mega Varnish, while hallways, bathrooms, kitchens and other areas subject to heavier wear will benefit from Manns Trade Extra Tough Pro Floor Varnish or Bona Traffic HD. That said, an additional coat of single-pack lacquer is also a common way to finish residential areas subject to heavy wear.

A typical domestic application in 7 steps

1. Apply one coat of sealer or primer to the pre-sanded surface.
2. Allow it to dry for 2–3 hours.
3. Apply one coat of floor varnish with a microfibre roller or another floor finish applicator.
4. Leave it to dry for 4–6 hours.
5. Denib the surface with a rotary sander and 150–180 grit paper, then remove the dust.
6. Add a second coat of water-based floor lacquer, again using a roller.
7. If you want a deeper, fuller finish, you can apply a third top coat of varnish.

Oiled floors

Instead of sitting on the surface of the wood, oils sink in for a warmer, more natural look. Here’s how to achieve it…

• Sand through the grit levels until you reach 120 grit, which leaves the wood’s pores open enough to accept an oil finish.
• Apply a thin coat of oil using a mohair roller, floor applicator pad, lint-free cloth or special solvent-safe squeegee.
• Leave it to dry for 4–8 hours, depending on the product being used.
• Lightly sand or denib the floor with a Scotch pad or fine-grit sandpaper.
• Vacuum to remove all traces of sanding dust created when denibbing.
• Apply a second thin coat of oil.
• Wait 12 hours for everything to dry and settle.
• If required, buff your floor to improve the sheen.

Part 2 – Coming next week

Next week, in Part 2 of our Wood Floor Sanding and Maintenance Guide, we’ll look at how best to maintain and look after wooden flooring with the help of a wood floor cleaner. In the meantime, if you’d like to discuss how to bring your wood floor back to life with an expert, feel free to call our experienced staff. They’re always happy to show off their skills, advise our customers on the best products and pin down the best method for your particular project.