Refurbishing wood floors provides opportunities for contractors, says Richard Aylen.
ONE of the greatest benefits of solid hardwood floors is their longevity, and this comes about largely because they can usually be refurbished numerous times during their life.
We’ve become rather good at refurbishing wooden floors; after all, we have had a few centuries to learn, and along with modern machinery and a wide choice of durable and reliable floor finishes we are well positioned to make the most of a solid hardwood floor’s longevity and sustainability.
Refurbishment also provides us with the opportunity to change the colour of the floor if we want to, rather than simply replacing it if we decide to change our décor.
Manufacturers of wood floor finishing systems aim to provide products that are easy to use, that protect the floor and look good. Anyone who has used lacquers, oils or any other treatments for any length of time will know there are some basic rules for using these products; rules that are fairly consistent from one manufacturer to another; for example, having the right site conditions, achieving a good standard of floor preparation, using the right application tools and so on. It can be a problem if we don’t understand why these rules are needed and so in my column this time, I would like to talk about what lies behind these basic rules.
I believe that having a good understanding of how a product works and why it needs to be used in a certain way gives you full control of your work processes and you can make informed judgements about the work you are doing.
Just to be clear, I am not intending to provide a comprehensive guide to floor renovation and maintenance. If you are looking for that you will find that FITA and the CFA provide some excellent training courses to hone your skills in this area, and companies like my own; Junckers, will be happy to take you through the benefits their products can offer. Instead, I am going to focus on the products we use to coat the floor and how they behave.
Floor preparation
Preparation is probably one of the most important stages in the process as it is usually difficult to rectify preparation issues later on.
Whether you are fully sanding the floor or just abrading the surface ready for a maintenance coat of lacquer you need to ensure the floor is clean and free of dust, grease, cleaning agents and other contamination.
Most people understand that you cannot apply a new floor treatment onto a contaminated surface as this will effectively prevent the new coating from adhering properly.
Effective dust removal is crucial, and to do this effectively you need to vacuum; sweeping is not enough. Dust contamination can lead to a variety of issues. If you are sealing a dusty surface, the coating will contain visible dust particles which are unsightly and feel rough. What many people do not realise though is that dust can sometimes cause lacquer to peel off because it may not adhere properly.
Thorough vacuuming will remove dust and debris not only from the surface but from the joints between the floorboards as well. This is important because if the joints contain dust it will be dragged out onto the floor surface during the lacquering process.
Also, if you fill the board joints with a mixture of sawdust and lacquer (and perhaps a few years’ worth of dirt if the client’s maintenance procedures have been below par) you will create hard filler that can result in a variety of longer term problems. Effective dust removal is just as important after full sanding, as it is if you are just abrading the surface between coats.
Wood dust is also known to cause discolouration of the floor. If you are sanding an oak floor and using water-based primer and lacquer, a very common combination, the water in the lacquer can react with the naturally occurring tannin in the oak. This results in dark brown patches and the only way to remove these is to sand the floor and start again.
Use the right primer
I have talked in detail about primers for wood floors in my previous columns, but it is perhaps worth having a brief recap on what primers do and why we use them.
Primers are used mainly in combination with water-based lacquers and their main purpose is to prevent the lacquer from gluing the floorboards together. But the primer, because it will be the first coating applied to the bare wood, will also tend to determine the final colour of the floor.
Solvent-based primers tend to bring out richer, warmer colours and water-based products tend to make the wood appear lighter. The type of floor you are coating may also influence primer choice. Tropical hardwoods, which may contain significant amounts of natural oils will often work best with a solvent-based primer such as Junckers SB primer.
The same type of primer is also better suited to patterned floors such as herringbone or chevron. When using water-based primers on these types of floors it can sometimes be difficult to avoid a patchy finish, and for this reason water-based primers are mainly used on plank or strip floors.
Most manufacturers will offer coating systems; a collection of products such as primers and lacquers that are designed to work together, so the lowest risk option is to use products from the same manufacturer.
Use the recommended application tools
I would always suggest using the application tools and techniques that the coatings manufacturer recommends. There could be faster methods available, but they will come with risks e.g., you may inadvertently under or over-apply the product, flood the joints, or apply it unevenly.
Often the most reliable method is to use a roller and manufacturers will recommend the correct type for their products. Applicators which come in the form of a pad can be quicker to use but if you don’t fully understand how they work then you can get it wrong.
With my own company’s lacquers, we don’t recommend pouring the product directly onto the floor. If you are going to do this and you are fully prepared to accept the risks, then at least make sure you do it sparingly and spread the lacquer quickly, so it doesn’t flood the joints!
Be aware that water-based finishes can be applied too thinly if you are not careful but will actually look ok, i.e. the lacquer will cover properly, but this does mean it will wear out prematurely, so you need to gauge the amount you are applying in order to achieve the right film thickness. By contrast, if you try to apply a solvent-based finish too thinly you will see some warning signs where the finish ‘drags’ unevenly.
Flooding the board joints may cause irreversible damage to the floor. This is because many water-based lacquers can glue the boards together which restricts the natural expansion and shrinkage of the floor.
Site conditions
All floor finish manufacturers recommend the best site conditions for their products to work properly. Most will require the site to be the same as when the building is occupied and in use, ie not too hot or cold, and reasonably well ventilated. In order to dry and cure properly most products rely on water and other solvents being able to evaporate at a certain rate. During this process chemical reactions will be happening as the lacquer cures and hardens. If the conditions are too hot or cold the solvents will either evaporate too quickly or too slowly and this can affect the ability of the lacquer to cure and reach full strength.
It can also result in the final sheen or gloss level being patchy or wholly different from what you are expecting! The resulting coating will be weak and will wear out far quicker than it should.
Not too many coats in one day…
On a warm day when the lacquer is drying quickly it can be tempting to apply as many coats of lacquer as you can, to get the job finished quickly. Unfortunately, this carries a risk, and this is why many manufacturers recommend only a maximum of two coats in a day. If you apply too many coats in quick succession, you will have a very thick layer of uncured lacquer.
The excessive film thickness means the solvents will evaporate too slowly and this can result in the coating not curing to full strength, just as happens when the site conditions are incorrect.
Temperature: Goldilocks zone
When we’re talking about ‘normal’ temperatures onsite we usually mean the site needs to be within the normal comfort range for a person occupying the building – not too hot and not too cold.
That’s simple enough, but there are a couple of ways you could be caught out, even if the air temperature is a perfect 19-20deg C.
If you store the lacquer or other finishing product overnight in a vehicle or in an unheated store and use it first thing in the morning, even if the site conditions are perfect, the product itself may be far too cold to use. This is far more likely to happen in wintertime of course.
The time taken for a 5l can of lacquer or oil to warm up from say 5deg C to more than 15deg can be many hours so bear this in mind if you are having a courier delivery in winter on the same day that you plan to use the product, or if you load it into your van the previous evening.
At the other end of the scale, you may sometimes need to think about the temperature of the floor surface itself. If there are large full-height windows in a south facing room the floor surface temperature could be too hot, even if the room temperature is otherwise normal.
This can lead to the product ‘flash-drying’ which means it may not level and flow properly. Timing the work to coincide with cooler conditions, or using shading to avoid over heating will make sure you can keep to the client’s programme.
When is it okay to cover the floor?
You should make sure the new coating is fully cured before you cover it with rugs, larger pieces of furniture, or lay floor protection material. You will need to check the curing time for the particular product you are using but as an example, many lacquers will take about three days to fully cure.
During the curing period solvents will be evaporating from the coating, and as we have discussed when talking about site conditions, if you inhibit the evaporation of these solvents the final finish may be patchy and lack durability.
Resealing an existing floor
(scrub and seal)
To ensure the new lacquer adheres properly you need to have a clean surface to start with, and you need to provide a good ‘key’. This is normally achieved by abrading the floor with a sanding machine or buffing machine fitted with an abrasive pad.
Be brave with this part of the process! Although you will be using a fine-grained abrasive it needs to be done thoroughly. You are aiming to achieve a uniformly dull surface with no shiny areas remaining. If you are too timid and merely make superficial scratches on the surface the lacquer may not bond properly and will peel off. Somewhat counter-intuitively perhaps, with a half-hearted approach you may also see a pattern of circular scratch marks through the new coating, so the more you abrade the floor the fewer scratches you will see.
If you do find scratch marks, unfortunately they cannot be disguised simply by applying more coats of lacquer.
Having a successful outcome for the job largely relies upon adopting good practice and being aware of the potential pitfalls. And so, to wrap up, I can add two further suggestions that may provide useful information if you should need to deal with customer complaints.
The first of these is to keep a record of the overall size of the floor you are treating, and how many litres of each product has been used for the job. This can be used to compare the actual amount of product you applied with the manufacturer’s recommended coverage rates.
If needed you could even back this up with copies of delivery notes, if you placed a specific order for your customer’s floor with your supplier.
The other suggestion for good practice is to keep a record of the batch numbers of all products you use. This is often the only reliable way to check out any claims that the product might be faulty. Manufacturers will retain production samples for every batch they make and will usually carry out batch tests upon request.
www.junckers.co.uk
Richard Aylen is technical manager, Junckers
