Hi everyone,

I am staining and finishing an existing hardwood floor in a home we recently purchased. The floors are red oak and we think they are roughly 30 years old. I have sanded the floors down with 20, 36, 60, 80, and 120 grit with a pad sander.

We are looking to stain the floors with a darker color. We are going to stain it with a water based stain (Saman, Wheat colour). For this process I am making sure the existing finish is completely gone. Some areas I've had to sand by hand, and the majority of the finish is gone. The problem I have is places where there appears to be a tiny amount of finish. I understand existing finish needs to be removed, but I don't know what's acceptable or not.

Here are some photos of my floor and the issue I'm talking about.

Here is an example of a bad spot that I already know needs to be sanded more.This picture is to highlight the difference between a spot covered 100% by finish and one that only has a 'ring' of finish.

A tiny amount of finish with the grooves of the wood.

An example of a finish 'ring' I have been finding. the finish is mostly gone, but a ring is left there (I am able to sand this away with a lot of work).

Another example of a 'ring' left from existing finish

My question is this: Do I need to keep spot sanding the areas I posted pictures of above, so there isn't any finish left at all? or are those areas okay for me to stain now? I don't want to mess up the new stain, even if it means putting more hours into hand sanding. I've already put a lot of time into this, so I don't mind putting more time into it (if it means I get a better result).

I am looking for any input or advice that would help me. Thank you very much!

Five grits? The first two should take care of any previous finish. Don't keep making fixes with different motions or grits. They will stand out when any stain is involved. Pete can better answer in detail what you need. Your photos are too intense really. Any inspection should be done by a standing position.

First, I have been told that Saman makes a special stain for floors. Are you sure that this stain is recommended for floors?
It is hard to get enough finish off to be sure that the stain can penetrate the surface without using a drum or belt sander. A random orbit sander with 80 grit to get the finish off any stubborn spots will save time, then go for finer grits.
Have a sharp scraper and bastard mill file and some 80 grit hand sanding paper handy if you find any remaining finish as you stain. The scraper should be sharp enough to make a shaving as you draw it along the grain, then hand sand to open the grain for the stain to penetrate evenly and blend in any spots where finish has remained. Sometimes just hand sanding will do, but you can always use the scraper.
Stain in strips a couple feet wide from wall to wall along the grain so you make easy work and can stop without lap marks.