Dear all,

I have a herringbone wood floor that I have sanded and varnished three years ago (it was in pretty bad shape back then already). The floor is pretty worn and thin (+/- 6 mm) in some places, but fine in others. The floor runs through the living room/hallway across +/- 40 m².

I would like to know whether sanding again (maybe only by a little since the wood is thin here and there?) and oiling it instead of varnishing it might be a good idea as I don't feel like replacing the entire floor with new parquet and would like to salvage it if possible - even if it's short term. I want to reduce the 'grayish' marks and dark brown spots (water damage?) and make the floor a little more uniform in color as a whole. I've included some images to show you those spots and the floor in general.

Any ideas/comments would be most welcome,
Thanks in advance!

Sam

That old varnish wears off in doorways first and there is where the flooring will be the thinnest. If you take care of a modern film finish it will last a lifetime and have the easiest maintenance. Smooth floors are the easiest to clean, and this is the finish I recommend in a kitchen or dining room. I also recommend to take your shoes off and leave them at the front door. Keep the grit out!
If you are looking for a finish that you can touch-up as it wears, then an oil finish will be your choice.

Thanks for the reply. I think I'll go for oiling.
Would you advise to sand it first to get rid of the varnish?
What grit?
Any experience with adding some color pigment to the oil to make it look more uniform?

Good luck with your floor if you are going to try sanding it yourself. Parquet will be a special sanding problem because of the 90 degree alignment of the slats.
Finish with 100 grit on a buffer so you don't see cross grain scratches.
You will need to be extra careful with an oil finish. Use a colored stain that is made by a reputable company, you won't need to add any extra color.A floor sanding specialist in your area will help you get the job done and it will be beautiful.
Your floor is special.
How long did the varnish last? Maybe 50 years?

OK thanks.

I have sanded and varnished it 3-4 years ago. In most places the varnish and the parquet is still in top condition, but in others not. Most troublesome places are the ones close to the doors, and this is where the parquet was in bad state already when I bought it.

My only concern is that those spots are already quite thin and that sanding them again might cause trouble...

If this floor is 5/16ths flooring the strength of the floor is related to the sub-floor.
A thin floor like this can be sanded at least three times just like a thick floor.
The oak floor can be sanded thin and still be serviceable. The important part of refinishing this floor is the preparation. You will need to fasten the floor really well. A well fastened floor will need less sanding because there are no loose areas that vibrate independently, the floor is more like a flat surface to begin with. The fasteners to use have a sharp point which can split the thin strips, but hold really well. The places where the flooring has minor gaps is where the fastening is most important. The nails take up space so this helps make the flooring tight. More nails are better than not enough nails to secure the oak to the sub-floor. Go over the whole floor, not just the heavily trafficked areas. After fastening the floor tightly to the sub-floor there should be so little movement that floor filler will stay in place when sanding after it is pushed in with a putty knife.
Once the preparation is complete you can sand the floor just like a thick wood floor.
Cracks between slats or even in slats which look like a split can be filled with wood patch and will not be noticed after sanding, but the patch material would need to absorb the color and oil that is used for finishing, so make a sample before you start to find the right wood patch.
Trying to sand and finish this type of flooring without a wood patch being used before the sanding starts is folly. You may use putty after the oil has dried, but oil will smear the putty if it hasn't hardened sufficiently, usually at least a couple of weeks. We try not to need putty by taking time to fill all gaps and nail holes with the correct wood patch before starting sanding, then again just before the 100 grit paper.
Using a modern film type finish should keep a floor like new for at least 5 years
before needing any tough-up for worn spots. If you have worn through finish already, then you may not be applying enough on each coat Or this finish is not protecting the floor well enough. Two part finishes are better for resisting chemicals and wear.
Remember if you are using oil there will be much more maintenance than a film type finish.
Most people who have an oil finish tell me they should have used a hard film type finish cause it starts to look dull and worn soon after the re-finishing. They really don't have time to spend on the maintenance.
If your varnished floor is getting worn and needs a touch-up, and you have never used wax or cleaners that leave a residue that won't clean off with water, you can apply another coat of the varnish after preparation, but if it has worn off so soon I recommend two coats at that time. One only over the worn spot and the second over the whole room. Modern water-based finishes can adhere to a varnish very well. If you like the color you can be very satisfied just re-coating a worn floor.
If you don't spend the time to prepare the surface before you start sanding you may not be happy with any type of finish after sanding to bare wood.

Thanks for your replies, very helpful!