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Sid Bourne On Recoating Wood Floors

Sid Bourne on recoating pre-finished wood floors

I HAVE received many calls over the years from wood flooring contractors asking me about re-coating prefinished floors. These are usually cases where the floor has been damaged or where customers have moved house and want the existing wood flooring resanded.
For example, one unfortunate contractor was called in to inspect a floor where there were deep white scratches. He decided on a complete resand with the big machine.
To start he placed a 60 grit on the machine. No sooner had he started to go over floor than – horror of horrors – the machine took the walnut face completely off.
He immediately stopped and, on closer inspection, he noticed that the face was only a thin veneer; it cost him a new floor.
I suppose you could say that this was an honest mistake. True, but it could have been avoided. Fair play to the contractor, he did pay for a new floor, but ouch! It was a painful and very costly error.
I have stated many times in the recent past that sand and finishing will become a serious money earner for those who choose this trade.
However, there are some very important things that you as a sand and finish expert need to do if you are going to be on the ball. Firstly, as illustrated by the case above, make sure you know what you are sanding before you begin.
Take the modern day engineered products, not including the cheap and cheerful ones; they are very advanced both with finish and visual appearance.
So unless you are an expert in wood it can be very difficult to tell a quality engineered product against a genuine solid wood floor.
So how should you approach a request for re-coating of a pre-finished product? An engineered wood floor can be normally identified simply by walking over it and tapping the face.
However, if it is glued down this becomes more difficult. If you unsure, take up a door bar or skirting to check if it is engineered.
Most important, check the wearlayer thickness. If it is a solid floor check to see if the wearlayer has been sanded before; or it may be a thin solid floor with less wearlayer than an engineered product.
Also check the finish. Try to establish who manufactured the floor. If you know, phone them and confirm what type of finish they applied. This is very important. For example, if it is an aluminium oxide or ceramic finish you will need to tackle it in a completely different way to how you would approach a standard urethane finish.
Aluminium and ceramic finishes are sold as almost impossible to damage and they are very good. However, when it comes to sanding or, even worse, screening, they will give you a problem if you tackle them in the wrong way.
After inspecting and confirming the finish, decide whether to do a complete sand and finish or a re-screen. If you re-screen it is a good idea to do some simple tests for contamination.
This can be important if you do not know if the floor has been correctly maintained or if a seal polish of some description has been used. It may also have been oversprayed with furniture polishes.
One easy test is to scrape the surface finish. Then rub it between your fingers and if it rolls into a supple ball then you have a contaminate to deal with. If this is not removed it can lead to the peeling of the new finish. If you are in any doubt I always recommend that you do a test patch.
Some contractors tell me they don’t have time to do a test patch. My response is to say that you cannot afford not to test, because if there is a problem you will have to make the time to go back and rectify it.
Once you have all your facts about the floor you can proceed. If you have to tackle a known problem factory finish I strongly recommend that – when pricing for this job – you allow for a lot more time and for more screens or papers to be used against the standard finish. So be aware.
Here are some tips for taking on aluminium or ceramic finishes: If a complete re-sand is required then I suggest that you think logically. You are in fact grinding an abrasive against an abrasive and it is difficult to get a good first-cut.
What I often do with excellent results is first to start with an 80 grit which will open up the surface of the finish. I will then drop my grit to 60 and then work back-up grits to whatever grit finish I decide on. This, of course, depends on my finish.
If I am to finish with a urethane, I start with and 60, then 80, then 100, then 120, and sometimes – depending on what I am trying to achieve – I then screen using a 150.
Please always vacuum before each sanding procedure.
For re-screening do be careful that you don’t actually leave more damage than when you started. If using traditional screening methods, I will always put my new screen on and quickly run over a square of plywood which takes off the real sharp damaging abrasive. It’s advisable to carry a piece of plywood in your van.
I suggest that you start with a fine grit and work your way up if you find that the fine grit is not aggressive enough. If you screen, check your scratches pattern. Check to see if they are visible when you wet a clean white towel and wipe over the scratches.
If this water covers the scratches then you know your finish will be fine. If not then you will need to rescreen to remove.
When doing this always remember to explain to your consumer that it is impossible to get a factory finish. Get them to sign a piece of paper confirming that you have explained to them what to expect.
This is not something that should be abused when you do a bad finish job. If done correctly and a quality finish has been applied using the correct applicator then the finish you achieve will certainly be a ‘perfect finish’ viewed from a standing postion.
This explanation to the consumer about what to expect is important, because you may get the occasional person who inspects on their hands and knees trying to find fault. And they will succeed in doing that even with a factory finish.
Make it clear that you should always inspect the floor from a standing position. Remind the customer that the floor is only for walking on, not for eating their dinner off.
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This article has been reproduced from the Contract Flooring Journal. You can find them at