Hardwood floor refinishing is a subject that is fairly misunderstood. The mistake people make is in thinking its an easy straightforward process. “All it comes down to is applying sandpaper to wood and then applying a finish,” goes the thinking, “how hard could it be”. On the contrary sanding and refinishing hardwood floors is a fine art.
There are lots of articles on this website that will give you the technical instructions to enable you to sand and refinish your floors. However, in this article, I want to introduce some key concepts that will help you better understand the floor sanding process. You will learn the one key difference between the average DIY enthusiast and a professional floor refinisher, something you can implement easily.
This will hopefully convince you to use the methods and machines that I recommend. That is, rather than listen to the advice of the guy at the rental shop.
Does sanding really “damage your floor?”
One of the of the most common fears among prospective DIY floor sanders is the possibility of damaging their floors. Often they have no idea how any why it will get damaged, while others learn that “if you use a drum sander (big machine), you will damage your floors because they are too powerful.”
Here is an example of this ‘damage’:
Let me address this right here, right now.
Most of the drum sanders that you can rent to sand your floors are actually lacking in power! As you would see in my video course, in which I use rental machines, it takes me a very long time, going over the same area again and again with the coarsest grit, just to get it flat and clean.
It’s not the power of the floor sander that inevitably causes the damage.
However, if you don’t use the machine correctly, you can create a dent in the surface of the floor.
People that don’t research the subject whatsoever and don’t realise they have a problem, can cover their entire floor in these dents, much to the amusement of floor refinishing professionals across the globe when surveying floors for estimates.
To get a good idea of how to use a belt or drum sander (big machine) click here, but in short, these dents are created by lowering the drum of the big sander on to the floor before you start moving forward as well as stopping the machine before you lift the drum off the floor.
They are created when the abrasive is in contact with the floor, but the machine is not in motion (moving back or forward), it is just stood still.
Well, my friends, there is a simple trick that can help to mitigate this to a huge degree. All you need to do is use a 100 or 120 grit paper while practising your big machine motion.
- Start moving forward
- Lower the drum onto the floor
- Keep moving towards the edge of the floor
- Lift the drum off the floor
- Stop moving
120 grit is so ineffective at sanding through finish or removing a lot of material that even if you make a mistake, it won’t damage your floor. To the extent that it does create an extremely shallow dent, it will disappear with the first proper sanding pass. I have used this technique to teach people to use a big machine in 30 mins. Just teach them the motion, put a fine or even used fine grit sandpaper on the machine and let them thrash it out until they have it sussed.
One of the very frustrating things about refinishing hardwood floors yourself DIY, is finding countless sanding imperfections (scratches) in the wood that weren’t visible until you applied the finish. Now the finish has been applied, they are standing out like a sore thumb.
The best way to mitigate this is to stick to the floor sanding grit sequence guidelines in good faith.
Starting from the top, you want to use a coarse grit sandpaper to remove the old finish, dents, scratches and to level the floor. This is 36 or 40 grit. Occasionally, professionals may use 24 or even 16 grit before 36 or 40, on floors that are very uneven, hard and/or covered in difficult to remove materials like polish or carpet glue.
You should use this coarse grit to get the floor completely flat and clean. Don’t leave finish or dents in the floor, telling yourself you will remove it on the next grit. This will just make the job harder and more frustrating. Keep going until there are no old finish or dents in the floor before moving onto the next grit.
Then we have the medium grits, 50 and 60. These grits are for bridging the gap between the course grits and the fine grits. This is where a lot of mistakes are made. When DIY’ers see their floor clean and flat after sanding it with the rough grits, they think they can skip to the fine grits. “Sure it might take a little longer to get the scratches out with this one finer grit, but it must be quicker than doing two grits,” goes the thinking.
It may even be quicker, but you are almost certainly going to leave scratches in the floor that are going to stand out like a sore thumb when the floor is finished.
Then you can move onto the grits, 80, 100 and 120