I now own a deck where the previous owner (for some reason) stained half of it a year or two ago (they did mostly the inside). I'm lucky to have the same product that was previously used. If I stain the rest of the deck, will I end up with two very noticeable colors? If yes, is there something I can do to reduce the differences?
Note, I will clean as much as I can before doing anything.
You'll have to eyeball it. You'd stain the unstained & wipe off the excess where it looks pretty close...test wiping here & there. Then, let it dry & see how close or far it is from the inside portion.
If it's too far or too dark, then you can sand it out a little, but that's a crap shoot & it's better to just let it weather & sun down by itself. If it's too light you just add & immediately wipe off without waiting or waiting much at all. Adding stain to the inside portion will be very difficult to eyeball if it's not in the sun, so I wouldn't try doing anything there.
I would stain the rest of the deck, let it dry fully, and stain the entire deck again. The variation should be minimal at that point.
You could also try to darken or lighten the stain slightly. If it has been weathered then the color will have changed. stain a very small patch close to the stain portion of the deck. Darken or lighten the stain to match as close as you can from there.
Most of the time you can simply put a little darker stain (i.e. dark walnut.) And to lighten it you can add a little lacquer thinner or paint thinner.
