Thin ridges up and down floors

Q: I just had my hundred year old oak floors sanded, stained and polyed by my contractor. He cut the floors, which are either 12″x12″ square parquet or 2″ long planks, with a rented belt sander and used a hand held edger. The floors looked normal once sanded, with some scratches here and there, but good for their age.

They looked normal after the stain as well, but once the ploy went down thin ridges appeared up and down the majority of the floors. Are these marks from the sander? Can the poly be buffed and screened or do we need to start over and use a finer grit to solve the problem? Also, on the new pine planks in another room, the poly appears scuffed and the stain appears noticeably lighter along two of the four walls.

A: It sounds like the “lines” you mention are probably in the parquet block. Since this type of flooring is sanded cross grain on every second square, those squares in particular will develop heavy scratching. Such floors need to be polished with a polisher and 100 grit sandpaper disc and polisher, then screened with a 100 grit screen as a final sanding in preparation for any staining and finishing that is to be done. Buffing and re coating will not make such lines or scratches disappear.

Again, Pine can be particularly difficult to deal with when staining. Down the 2 walls are lighter because they ended up somehow being significantly smoother than the rest of the floor. The only way to properly fix this is to have the floors sanded again and start over.