I regularly have customers that have tried to sand their floors, made a right pig’s ear of it and have then called me in to correct it.
The first mistake that people make is they think that floor sanding is simple! Well, it is when you know how! They think that because they applied a bit of sandpaper to a piece of wood in woodshop class, they know how to sand a floor like an expert. How hard could it be? This is a question I get from some friends. They think there’s nothing to it, just gotta sand it down and lacquer it.
Well, unfortunately, it doesn’t quite work like that. For one thing, it would take a very long time to do by hand and therefore must be done by machines. Namely, very heavy powerful machines. Without experience or some guidance with these machines, there’s a very high chance you are going to do a poor job. Do some research (on this website!) and make sure you know everything you can know before taking on the task.
The second mistake I see time and time again is that people think that they can sand a floor starting with 120g sandpaper. They are too concerned with not removing too much wood that they end up not even taking all of the previous finish off! The floor looks nice and clean so then they put down their lacquer or oil or varnish and BAM, that’s when they see all the previous finish that hasn’t been removed from the floor. As they apply the new finish, it reacts differently to areas where there is bare wood and the areas where the previous finish is still on the floor.
I have seen this turn floors GREEN!
Just so you folks know, I have a very heavy powerful floor sanding machine. I almost always start with 36 grit. Rarely I will start with 60 grit because the floor is quite smooth and there’s not much damage. Once in a blue moon, I will start sanding with an 80 grit. What are the conditions needed for me to start with an 80 grit? It needs to be a very well laid, unfinished floor. If your floor has the normal wear and tear and a previous finish, there’s a good chance you are going to need to start on a 36 grit sandpaper.
Be sure to check out How To Use a Belt or Drum Floor Sander so you don’t make common mistakes when using a floor sanding machine.
P.S There is a video on youtube about “how to refinish a hardwood floor” and it has over 300,000 views. And it is dead wrong! He recommends using a finishing machine. A stand up orbital sander that should only be used to smooth the floor after the initial sanding. I have had customers that have used this on newly laid, unfinished floors and after spending DAYS on it, they call me up because they can’t get it smooth.
These machines are not made for removing lacquer, oil, dents or scratches. They are made for smoothing the scratches from 100 or 120 grit sandpaper on a belt sander! So the floor needs to already be clean and flat and very smooth in order for these to work. Such a shame this video has become so popular!
Don’t fall into these traps guys, get prepared.