So you have an engineered oak floor that needs a new lease of life, sounds simple but remember you are not dealing with a solid wood floor so first things first, work out how thick the veneer is on the floor you are going to sand.
The floor above was very flat and found to have 4mm of veneer, which meant i had plenty to play with, that’s just a term of phrase by the way, veneers should not be played with and the aim of my game is to leave as much timber on the veneer as possible giving maximum lifespan, however this floor was oiled in dark oak, so i will need something a little harsh to remove the oil that will have penetrated a little into the timber.
I decided on a 50 grit sanding belt for this job, rough enough to remove the oil but fine enough not to remove less than a mm in a pass of my machine.
As you can see from the pic above the 50 grit just about removes the oil although there is some still visible, this is perfect as it shows i’m not remove excess timber, just enough, the remainder will sand off easily with a finer 80 grit, which i will use next.
All previous finish removed, i will now edge round the edges using just an 80 grit on the spinner (edge sander).
At this point you have 2 options, well you may not have a trio orbital sander, so you may have just one option.
The floor is now at an 80 grit, If you only have a belt floor sander you will need to use a 120 grit to give a final sand before you varnish, If you have a trio or a multi buffer with sanding pads attachment, go over the entire area with a 50 grit, 80 grit and finally with a 120 grit and rotary sand edges at 80 grit and again at 120 grit. Vacuum twice and the floor is now ready to receive your desired finish.
I took less than a mm off this 30 m2 floor which equated to one dustbin liner of dust, I’ve seen other floor sanders do a similar area size and take 4 bags of dust away, Not good.
Nothings set in stone with floor sanding, some operators i’ve found use the same process for every floor, they use harsh grits to speed up the process which is good for them but not great for the life of your floor. Ask your sander what grits he will be using and why, It’s not a stupid question.