Do over please. You're making too big a jump between your grits. 60-80-120-220 or so please. I'm assuming you're using a random orbital sander?

Hi Joe. I used a corner hand sander, a dremel hand sander and my hand with sand paper at different times. I used a 60 , 80 ạnd 120 at different times too. So what can i do tômrrow to even it out? Thanks for the reply!

I guess all i can do is sand it again but with what grit? Do in use a 80 only? 110 only?

Start with 40 grit or hand scrape it off, before continuing with 60-80-100 and then 120. You still have a lot of work.

You need more PRESSURE on the machine. The 'bite' of the low grit (like 40 grit) isn't enough. You need some UMPH behind that grit. You will also need to LIGHT that area. A mechanic's light (the bright bulb sitting in a metal cage that is attached to a 40ft extension cord) will do it. You need to SEE what you are doing.

You will need MANY pads of each grit to get this down to raw wood. The 40 grit with WEIGHT behind it/on top of it should chew through the old finish quickly. Then you move to 60grit and then 80grit to make sure you've gotten all the little bits left over. Once you are 100% sure the old finish is gone you then use your 'finishing' grits (highest grit like 120).

Agreed on the suggestion to get a good work light so you can see the sanding marks. Never jump from one grit to more than 50% more on the next finer paper (e.g., from 60 to 120 is 100% jump - go from 60 to 80 or 90, and then to 120).

Also, because that looks like pine, it will be blotchy. Using a pre-stain wash coat might help (I use dewaxed shellac for that exact purpose on softwoods).

If the corner sander you refer to is a square vibrator sander, you'll be rather old before the job is finished properly. I suggest that at the very least you purchase an orbital sander. You'll need to start with grit closer to 40 or 60 to remove most of the old finish., then move up in grits until you reach 100 or 120.

Penetrating stain used on flooring is made to be applied to freshly sanded wood. You may also want to consider using a 2" wide razor scraper and possibly paint stripper on the areas with heavier finish left intact. A smaller 1" or 1-1/2" scraper can be used on the nosings. In fact, if you scrape the treads well enough you could get away with moving straight to 100 grit like the professionals do in the corners of every room they refinish. Sharpen the blades often and they'll remove the finish without tearing the grain. Normally you scrape with the grain but for difficult areas you can go on a shallow angle of turn the scraper slightly so it's at about a 15 degree angle.

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You can strip the stairs using a smooth planer. It can be faster than sanding. If, you know how to work a planer.