I stained red ok floor in 1935 house with jacobean. There were swirls in an area so thought I would orbital sand them away and just restain. Now it is very obvious ...i have sanded back with belt sander grit 80 but the wood is not absorbing the stain evenly as it did first application. The blond area is bare sanded and the 2 tone is where I am trying to get stain to absorb but is much lighter. I am trying to prevent starting all over. Thank you for any suggestions. :)
It really is going to be next to impossible to match up those various areas where you have tried the sanding and re-sanding. My recommendation, if the flooring material still has enough depth to the tongue and groove to permit more sanding, is to re-sand the whole floor uniformly. That may be best done by using a drum sander so as to get as even of surface as possible. Do be aware that operating one of those is tricky and in inexperienced hands can ruin a good floor very quickly.
Once you have cleaned the floor of all the sanding dust you should look into sanding sealer products that you can apply to the surface. These are designed to allow stain to be applied more evenly than just putting stain on raw open grain wood.
I agree with the first answer provided with some pointers...
Sanding sealer isn't required or used when staining hardwood. Most hardwoods will take stain uniformly. Pine on the other hand... If you use a penetrating stain, Minwax, instead of a wiping stain, you'll also avoid lap marks in the stain.
Also, don't try to do large areas at once. You should be working an area no more than 3 or 4 feet wide. Start at one end of the room and work towards the other. The idea is to work yourself out a door so you won't have to get on the stain.
From your pic, I would divide the room in to at least 3rds... Do one side of the room, then the other side, and finally work your way thru the middle section and out the door...
Pointer on sanding... The finer grit you can sand with the better. What I mean... As a one time professional flooring mechanic, whose installed as well as finished/refinished several million square feet of hardwood, I would have sanded this floor 3 times as dark stains require more attention to remove sanding marks because dark stain enhances them. My final sand, before buffing, would have been 120 grit. I would then buff with a 120 or 150 grit screen. The finer the sanding, the more closed the grain is and the less stain gets absorbed in to the material. Also, you must make sure to overlap everything. Overlap when sanding, staining, and running finish.
I've got so much info, but there's no way I could type it all out here... I'll answer any question I can however.