Wow, you are not kidding what you may find under that old carpet. I just bought this house and the entrance/hall, living room and third floor all had the same plain and somehwat worn grey carpet. Pretty boring for a 1890 home.
I did not do the refinishing myself - sorry, but I did remove all plywood and staples myself - that was a project in of itself!
I called 3 people and the first two came in and told me the parquet living room could be salvaged, but the hall and third floor were completely shot. Knowing very little about wood flooring I was all but ready to fix the living room, but lay carpet back on the hall and third floor because I could not afford all new hardwood with having just bought the home itself. The third guy missed the first appointment without calling and I almost signed with guy number 2, but gave him one more chance.
When the third guy finally came he had hair sticking straight out like a mun-chi-chi (remember those?) full of sawdust and his glasses were so dirty I could hardly see his eyes. Somehow he was able to view the floor and without hesitation he said "no problem", this is a beautiful red oak new york strip floor, hand cut with precision, mostly laid for doctors and lawyers at the time, .....
The living room parquet - same thing - he showed me how it was impropetly sanded the last time and how to see the subtle lines formed from doing it wrong.
Then he went to the third floor antique pine boards, licked his hands several times, rubbing the floor profusely and exclaimed the same thing - no way in hell I'd cover this up - it will have a glow you could never reproduce with any stain or chemical.
Needless to say he was hired on the spot!
We could not even see that the hallway was almost 100% quarter-sawn red oak at the time. And after it was sanded, I still did not know what this meant because all the pictures online have minimal "tiger-stripping" (as I call it). This site helped me understand that old lumber had many more rings and stronger accents that current lumber. Boy and I glad I gave the guy another chance!!!!!
First pic is after I ripped up the plywood, which was both glued AND nailed every 3 inches on center!! Woah, that was an ugly job pulling thousands of nails! They ultimately trowel filled the floor to fill the holes.
Pic 2 was after it was sanded
Pic 3 was after it was stained (to blend some replacement boards with old wood to minimize variation in the floor - worked VERY well) They pretreated each new board individually to help it absorb stain better and it really made them match VERY well.
Pic 4 is a close-up after it was coated twice with BonaKemi Traffic to help preserve the floor as it is not sandable again.