Even without knowing the kind of wood or condition, I can't imagine replacing wood flooring in an 1890 home. In my opinion, the value is in the original material. If the floor is in good condition, it may not need sanding at all; a screening and recoat might be all that's necessary and the patina would be retained. There are many threads on this topic, try searching the Old House forum. I live in a converted schoolhouse built in 1890. The fir floors had been covered with layers of linoleum, glue, paint ... they were a mess.. but looked awesome after refinishing. That was years ago and I'm planning to have them screened soon (aka buff and recoat.) What kind of wood is it? Do you have photos?

Yes, they had to sand it lightly and then carefully remove all dust and residue. I don’t get why you are buying this flooring to begin with though. I would never have bought it if I had known how poor the finish was and that the company didn’t care or stand behind their product. In the end, we spent much more than we would have if we had just bought a better product. There are quality wood and engineered floors out there. Why don’t you give them your business? I posted my experinece so that people could learn from my mistakes, not repeat them. 🙁

Thanks chief! Two of the gaps will be under the sofa. I can live with that but the majority are in more visible locations. I'm sure my guests are never going to get down in their hands and knees but it certainly will bother me. Not to mention all the dirt and dust that will get caught there! :(

I'm going to disagree with the other opinions in that this could certainly be caused by humidity and acclimation. Every wood pro knows that solid wood will absorb moisture and expand. It's rather unlikely that the boards would be milled to different widths and especially that it would vary in width along a particular board. In general, 4/4 lumber is cut to uniform widths then sent through a machine that mills and kerfs the bottom, mills the top flat and cuts the tongue and groove on opposite sides, all in one machine. Another machine generally adds the end matching. Unless something in the milling machine is moving, or the unmilled boards were too narrow, all pieces will be the same width as they exit the molder. Look at this video at about 1:30 to see the molder in action. https://www.youtube.com/watch?v=wc0N6m4RNdY What you're experiencing is probably the effect of moisture soaking in to parts of boards that were more exposed to humid air. Exposed ends will grow more than centers that are less exposed. Look at the your first full row from the top. On the middle board, the end is wider than the one to the left. In the next row down the opposite is true. It's likely that those ends were exposed to more humid air. The problem is exacerbated when the installer doesn't compensate, since the wide ends can kick the next row out of line, leading to more gaps on the edges and ends. The same thing could happen in very dry air with ends shrinking. Exactly how was the wood acclimated? Was it removed from cartons and wrapping? Was it stacked so air could circulate around all sides of every board? What was the temperature and relative humidity in the space during the acclimation period? What is the current indoor temperature and relative humidity? Is the floor nailed down? I had this happen with a very high quality Canadian solid wood floor. Fortunately mine was dark stained Walnut so once the floor was aligned properly and larger gaps were distributed to make two smaller gaps on each edge, the issue didn't show and once the whole floor acclimated in place there was no issue.