Refinishing a wood floor

Refinishing a wood floor

Written by Matt

How to refinish a wood floor?

Refinishing a wood floor yourself, rather than engaging an experienced floor refinishing professional? While a D.I.Y refinishing job may reduce the cost of the project? The time, effort, cost and eventual results may not be worth it? Either way, it is important to have the correct tools, equipment and information before deciding to do it yourself.

The process I use when refinishing a wood floor has developed over the years through both training as well as trial and error. In the early years I worked for a few companies which taught me “their way” of refinishing wood floors. As the years went on and my experience with different finishes and wood floors expanded, technology also advanced. As a result, the process I now use to sand and refinish is faster, easier, and produces better results than those who “trained me” over 2 decades ago. While the process(floor sanding, floor polishing, and floor coating) remains the same, the individual stages vary depending on the type of wood floor I am working on and the finish that will be applied. The following is an overview of the steps I use to refinish all wood floors.

1. Floor sanding

The first process of refinishing a wood floor is sanding off old coatings and level the boards. Please note, floor resurfacing is a more involved process and may require punching nails, replacing boards, or removing old floor coverings. To remove old coatings, 2 pieces of machinery are required.

  1. A drum or belt sander is required for the main areas of the floor. Experienced professionals will generally always use a 220v, 8, 10, or 12inch commercial belt sander as opposed to a drum sander. A drum sander tends to leave a “chatter” effect, as a result of the paper join. “chatter” is a pattern of waves produced by inferior or unbalanced floor sanders and is almost impossible to remove during the following polishing stages. Belt sanders are fitted with a continuous belt, and when maintained and balanced, eliminate “chatter”. Most rental machines are either drum sanders or a small, 110v, domestic belt sanders. Drum and belt sanders are very powerful, even the small rental machines will destroy a floor if used incorrectly, unbalanced or not maintained. Irreversible gouges, dents, and divots in wood floors are common when using a drum or belt floor sander without adequate training. These machines can be extremely dangerous in the wrong hands or without personal protective equipment. 
  2. Floor edger machines are used around the perimeter of the floor and other areas that are to small for a belt sander to reach. Professional floor refinishing contractors will almost always begin their training using a floor edger as they are smaller, lighter, and generally easier to use. Floor edgers are a handheld rotary sander that are fitted with a variety of 8inch floor sanding discs. Edger’s are loud, powerful, and must be correctly balanced before sanding. An incorrectly balanced or handled floor edger will produced the same problems other larger floor sanders will. The most common problems associated with edging are “gutters” and “swirl” marks that polishers will not remove. An experienced floor sander will smoothly sand all the way to base and kick boards. I connect my edger to a commercial dust control vacuum fitted with a HEPA filter. Most rental machines are old, unbalanced, and produce large amounts of dust when used.

Creating a smooth floor

  • When used correctly, old finishes, surface scratches, dents and gouges are removed from the floor with a variety of course grit sanding belts ranging from 24-120grit. Commercial belt sanders also have a powerful impeller that are effective at containing the dust created while sanding. Domestic rental sanders produce larger amounts of dust when sanding a floor that has been previously coated. ALL the old coatings must be removed and may take multiple sands?(not removing old coatings will result a botchy finish once sealers, stains, and new floor finishes are applied). These floor machines are so powerful that the user must be fluid across the whole floor. Pausing, dropping the clutch, or hitting a wall will result in gouges that will be visible in the finished floor. Excessive or deep gouges may require the floor to be re-sanded or replaced.

Floor edger
Floor edger

Filling

  • Once the floor has been sanded, and old coatings have been removed, the floor can be spot filled with water based putties. I generally walk over the floor and fill any nail/ tack holes, missing knots, or larger butt joints that that have been exposed during sanding. I never recommend flood, or trowel filling a floor with liquid putty. Wood floors are a natural product and will expand and contract due to variations in climate conditions. Flood filling floors with putty will eventually result in the putty cracking a falling out between the gaps(see picture below) in floorboards. Filling gaps between floorboards is not considered an industry standard I leave the decision to homeowners and clients.

gaps in floors
Gaps in floors

2. Floor Polishing

Once the floor has been sanded, it must be polished to remove the fine marks left by belt and edge sanders. These marks may not be noticeable to an untrained eye until the floor has been stained or coated. Professional floor refinishers use single, multi(or a combination or both)rotary floor polishers which may vary in size. These machines are very difficult to handle as they tend to “throw” the user around the room until they learn to balance them while polishing. Polishing is a critical process when refinishing as this is the final step before staining and coating. The fine sanding discs and screens used with rotary polishers vary depending on the type of finish used to coat the floor. I also use a smaller, handheld, rotary polisher for the edges, stairs and any area that larger polishers cannot reach. Polishers must be connected to a commercial dust control vacuum as they produce large amounts of fine dust that will cover your home and walls if used without dust control. Rotary polishers are not widely available in rental stores due to the difficulty in using them. As an alternative, rental stores offer a “square buff” style machine which is only effective at “cutting back” or fine polishing between coats or when recoating.

Floor polisher 320x180 1
Floor polisher

3. Floor coating

  1. By now you will have decided on your floor finishing products and purchased the array of equipment needed to apply them correctly. These include but not limited to, a painters pole, brush, applicator, roller, bucket, tray, gloves, non-marking old shoes, respirator, and cartridges. Solvents may be needed to clean your equipment after each use if oil-based finishes are chosen. Once your ready to apply the coat give the floor, including baseboards and surrounding area, a good vacuum.
  2. Before you coat the floor, be sure to monitor the ambient temperature and relative humidity. These are important factors for a professional floor contractor and the key to a successfully finished wood floor. Temperatures should not be too far above or below 20 degrees Celsius. If you choose to stain your floor, it may need to be water-popped(depending on the species)to allow stains to absorb evenly.
  3. After the sealer, or stain, has dried the first clear coat can be applied. After the first coat has dried(refer to manufacturer recommendations)spot filling any areas that were missed before coating the floor can be completed. This can be done with compatible color matched putty or fill products. When your satisfied that you are ready for the next coat you can begin the cutback, and polish stage with a rotary polisher or buffer fitted with very fine sanding screens or conditioning pads.
  4. Once the floor has been “cut back” thoroughly vacuumed the areas. The final coat is the most important part of the entire floor refinishing process and full care should be taken to ensure even application and drying. Floor coating is a skill that most professional contractors take years to master so don’t be disappointed if your floors show signs of flooding, pooling, bubbling, lap lines, or missed spots. In order to apply a floor finish correctly, you must apply evenly and quickly while maintaining a wet edge at all times.

The final finish

I continue to find the feeling of successfully refinishing a wood floor extremely satisfying, even after 20 years refinishing floors. I still experience challenges here and there, but the skills I’ve acquired allow me to overcome work through them. The physical aspects of the job are becoming more noticeable as I age and my days of refinishing a wood floor are definitely numbered. For this reason I am happy to help others and supply all the necessary supplies required when refinishing a wood floor. If you choose to sand and refinish wood floors yourself, take a look at the products I have available. I can assist you in the planning and supply of materials that will help you when refinishing a wood floor and likely save you time and money by avoiding wastage and mistakes.

Refinishing before and after

In this post I talk about how to refinish a wood floor. I talk about the various types of machinery used to sand off old floor coatings, how to coat a floor and the finishes I use and recommend.

Total Time: 3 days

  1. Floor sanding

    Floor sanding

    Evenly and effectively sand off old coatings from wood floors with rough grit sanding belts. Starting with a rough 24grit belt and progress down to 80, 100 or 120 grit floor sanding belts.

  2. Floor polishing

    Floor polishing

    After sanding off old coatings use a rotary floor polisher to smooth out the surface and remove marks left by belt sanders. Evenly polishing with the grain minimizes visible polishing marks in the final finish. Use fine mesh sanding screens in 80-180grit increments until the floor is smooth and evenly polished.

  3. Floor finishing

    Floor refinishing

    Apply 2-3 coats of satin or matte water based floor finishes by working in sections is to ensure a wet edge at all times.

More useful information…

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