We had in Germany a red color on our floorboard called oxblood (Ochsenblut).
This is how it looked:
We asked someone to grind our floorboard. Although we like the outcome, the border looks somehow blurry. Can someone guess why this happend? The ground has been oiled. I would like to know how this could happend and what is needed to fix it. Here are some example pictures:
When floors are sanded it's commonly done using two types of sander, a belt sander for most of it and an orbital sander along the edges. I think what's happened here is simply that the edges haven't been sanded enough, so some Ochsenblut remains.
The belt sander that is used for the majority of the floor is much more aggressive and capable of removing wood faster and more easily. The sander used at the edges is not as aggressive so more effort and care are needed to get the edges to match the main area done using the belt sander.
In short, more sanding (concentrated along the edges) should resolve this issue.
See previous Answer for more info, How to fix a wooden floor.
In all probability the floor was ground with a floor sander which cannot reach all the way to the wall. The last few inches would be ground using a hand tool which will not give the same uniform result as the larger sanding surface of the floor sander. It may be possible to clean up the edges by sanding further with an electric hand sander. Bear in mind that if you intend to finish the wood with stain the wood may not absorb the stain consistently between the center and edges due to any remaining original finish that would block absorption of the new stain. Since the wood appears to be a softwood, the stain may be absorbed differently at any location between grain lines due to the different densities of the wood. I recommend doing a test in a test area you can either hide or easily re-sand if you don't like the results. A pre-stain conditioner may also help.
