I'm seeing a new small hole on my hardwood floor since last week. It almost looks like it was a black spot before and then it became a hole. Is this because I didn't maintain the floor? or is it some sort of insect that did it?Black hold on hardwood floor

  • Is there an indentation around the hole, or is the wood flat except for the hole? – BMitch Aug 16 '12 at 1:01
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    there is no indentation, the wood is flat except the hole. It almost looks like someone pushed a burning cigarette through it. – coder net Aug 16 '12 at 1:03

It's likely a knot that came loose. The circular grain around it sure makes it look that way. The wood can turn blackish like this if water gets in there and sits which could easily have happened with a small hole like that.

How a Pin Knot is formed. Broken branch with encased dead twig, when the branch split under snow load, the twig slid through the surrounding wood, surviving intact. Same thing happens on tree trunks when small branches die and don't break off.

Future Pin Knot

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    Agreed, sure looks like a knot to me. +1 – BMitch Aug 16 '12 at 1:25
  • It could be water. I remember my wife used to put a wet umbrella in that area sometimes. How do I fix this? – coder net Aug 16 '12 at 1:40
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    This is certainly a knot. The grain flows nicely around it, so there is no question. Water on the floor could have gotten in, causing the knot to swell, then pop loose. You can fill the hole as others have suggested. – user558 Aug 16 '12 at 10:04
  • Yea- that panel should not have been placed there (not inspected prior to installation) it should have been used on the sides or not used at all. I would suggester removing it.. I know what a headache right? If I were to fill it I would not be proud of that. – Piotr Kula Aug 16 '12 at 11:46
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    Pin knot. A twig was fully engulfed during growth and since the embedded growth collar got cut off in manufacture, the core no longer was structurally tied to its surroundings and was just waiting for the right humidity change to slide right out. – Fiasco Labs Aug 17 '12 at 2:48

Clean out the loose or soft darkened area with a utility knife.

Fill the hole with stainable wood filler that is close to the shade of the floor, such as this

wood filler

After it dries, if you need to color it to blend in, try one of these markers.

stain marker

If necessary, make it just barely darker than the surrounding wood. It will look like a small knot. The colors can be blended by putting small dots of diferent colors next to and over each other. Go slowly.

Seal it with a touch of polyurethane with the same sheen as the rest of the floor (it looks like a satin finish in the picture).

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    Wood filler on a constantly moving floor? I do not think that is a good idea. The panel needs replacing. Its allot of work but it the best solution (and in the back of my mind I would have nightmares waiting for the wood filler to crack again.. arr) – Piotr Kula Aug 16 '12 at 11:43
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    @ppumkin -Manufacturers use wood filler to patch small voids in engineered floor all the time. Modern fillers have a polymer base making them much more flexible than old water-based wood putties. The hole looks about 1/4 inch or so and seems to be wider underneath than on top, making for a captive plug. I think the risk is small, and the effort to remove a board in the middle of the floor and replace with a new one that is properly set in may be beyond the skill of many DIYers. If tackled by a very skilled craftsman, I agree that board replacement is a more permanent solution. – bib Aug 16 '12 at 12:37
  • Fair enough. I would not do it anyway. It would bug the hell out of me. And I would not do it for anybody else either. I suppose to cover it up if you were renting a house.. then who cares right? :-) – Piotr Kula Aug 16 '12 at 12:39

Black holes are caused by a massive body collapsing in on itself, creating a dense object with a gravitational field so strong that the escape velocity is greater than the speed of light. Or, a knot falls out.

I'd drill out the dark matter around the hole, and fill it with a dowel to about 1/8 below the floor surface. Then I'd do my best finishing the top with wood filler.

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  • Of course, adding matter to a black hole will enlarge it, eventually causing it to engulf the entire earth. Or, its a knot. Are you sure we can take the risk though? – user558 Sep 22 '13 at 2:49

If more holes appear, then check for various woodworms, wood beetles, fungus, and mould. Sometimes, larvae create a symbiotic relationship with fungus. Treat wood by removing polyurethane finish, or drill a bit. Apply boron, creosote (not appropriate here), LOSP, or CCA (not appropriate here). Seal.

Get a dehumidifier to reduce relative humidity to at least 50%. Vacuum at least every 5 days, and avoid "dead" products, such as down, feathers, wool, silk, etc. since they can create a favourable environment for other pests.

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Agreed, replacing the panel is best however it is a lot of work. An alternative is to use a reamer cutter (a sort of parallel cutting tool-make sure you can get a plug cutter of the same size or slightly larger)slightly larger than the blemish. Cut in at appx 45 degrees in line with the grain. Cut a plug from scrap, with good waterproof glue (Cascamite is good) tap the plug in well moistened with glue GRAIN ALIGNED with the board. When set use a sharp chisel to 'nip off' the end of the plug and finish with fine sanding and local refinishing of the floor. One will be left with a barely noticeable oval plug grain matched to the surrounding floor.

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