Next, I will introduce very common filler that we use them widely in decoration- wood putty.
Wood putty is very common and widely used wood floor filler. Painters use it to fill nail holes between coats of paint and on stained wood work. Flooring contractors use it primarily between coats of oil based polyurethane. You can use it on a floor that is already finished without coating over it, the color stays fairly true but since it dries extremely slow, lighter colors will collect a lot of dirt and end up dark. This filler is made of calcium carbonate, boiled linseed oil and universal colorant.
Calcium carbonate and linseed oil are cheap, but over time it proved easer to buy wood putty already made. This product is very similar to window glazing compound, years ago wood flooring contractors would mix universal colorant into window glazing compound and use it as wood floor filler. If your filling a floor between coats of oil based polyurethane, then this is the filler of choice. Never use this filler under water based polyurethane. If you're not coating over this filler with polyurethane, you will need to wash off the oil smudges that will appear on the floor around the filled areas.
