Anyone can start a floor sanding project but not anyone can properly finish a floor sanding project. For a professional floor sanding specialist to reach that high level of smoothness on your floors he had to do an advanced training course and then work as a trainee for a few years. But many people seem to think that it must be pretty easy so why not do it yourself for cheaper?
To be able to start a floor sanding project you will need some basic tools. You can hire the floor sanding equipment from your local hire centre. Here is the list of the tools required:
a. Floor Sander – belt or drum
b. Floor Edger
c. Sandpaper belts or sheets starting from 36 grit up to 120 grit
d. Sanding discs starting from 24 grit to 120 grit
f. Dust mask
h. Brush & Tray
i. Roller & Handle
j. Masking Tape
k. Small Sander
l. Hammer & Hand Saw
Assess the job. Find all the nails and hammer them down. Repair any imperfections. Prepare the room for the first sanding.
The first sanding can make or break the floor. If the floor is very uneven or if there is paint on the floor or carpet glue, it would be a good idea to start the floor sanding operation with 0.24 grit sandpaper. You cannot start with 0.24 grit sandpaper and then move to 0.60 grit sandpaper because the scratches created by the 24 grit sandpaper have to be removed in stages. You start with 0.24, then 0.36, then 0.40, then 0.60, then 0.80, then 100 grit. Otherwise, the scratches created by the first sanding will be visible after you apply the first coat of varnish.
If the floor looks ok, start with 0.60 grit sandpaper and follow the process up to 100 grit. There is no magic remedy, you will have to take your time. Floor sanding is a slow process and the more time you spend doing it now the better the finished result.
After you have sanded the whole room, you will need to use the edger. The edger is designed to remove all the imperfections from around the skirting board area and any areas where the big sander does not fit. Take your time and use your common sense. Spend the same amount of time on all areas.
After you are done with 100 grit, you will have to start the fine sanding. At this stage, you need to assess the floor and if there are issues or gaps, this is the time when you fill them in. Sand the floor one more time with fine 120 grit sandpaper and save all the dust. In a bucket or tray, mix the sand from the sand bag with a gap filler. You can buy professional solvent gap fillers from Junckers and Bona. Junckers Prefill, Junckers Basefill or Bona Mix & Fill are three of the most popular gap fillers. Mix 1 L of gap filler with some of the dust until the mix looks like a thick cream. With a wide scraper, fill up all the small gaps 0 to 0.5 mm. Take a 1 hour break until the gap filler dries. 1 hour later sand the whole floor again with 150 grit sandpaper. If you have done it right, all the gaps should be filled and it should look like one flat surface. Job done. Prepare for finishing.
Vacuum the whole floor a couple of times and inspect the floor. If you are happy with the finish, you can apply the first coat of primer. Use a small brush and start with the areas around the skirting board and all the narrow areas. The open spaces you can prime with a roller (any short hair roller). The most popular floor primers:
A primer is not a varnish. The primers job is to even up all the imperfections on the floor and to create a flat base for the varnish. A quality water based floor primer will seal all the pores and it will not allow the wood to absorb more varnish than needed. A primed floor will dry faster.
It should take around 1 hour for the floor to dry after priming. One more sanding is required if you are looking for a perfect smooth surface. After the primer has dried, most of the tiny spikes that were left after the last floor sanding operation, will have gotten hard and it will make the floor feel rough. A quick re-sanding with 150 to 180 grit sandpaper, will remove all these spikes and will leave the floor perfectly smooth and ready for varnishing.
Apply the first coat of varnish from north to south. Apply very thin coats. Allow up to 2 hours to dry and then apply the second coat of varnish. Job done. It sounds complicated but if you follow the process, the results will amaze you.
Avoid solvent based floor varnishes. Solvent based floor varnishes stink and takes many hours to dry. There are quality water based floor varnishes available that do the same job, look better and are odour free. Use two pack water based floor varnishes to enhance the protection.
Staining & repairing wood floors is a bit more complicated and you should only start these jobs if you are very handy at DIY jobs.