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Understanding The Limitations Of Wood Filler

by Canadian Sanders

Understanding The Limitations Of Wood Filler

Understanding The Limitations Of Wood Filler 

Wood filler is not a magic solution to fix all issues with hardwood floors. It can only be used to mask small holes and chips. It’s essential to understand the limitations of wood filler and not rely on it to solve bigger problems, such as large scratches or holes. The examples provided in the article clearly illustrate how, even after filling, long diagonal scratches and significant gaps remain visible and can look worse. 

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Wood Filler Is Not Permanent 

Although wood fillers can temporarily fill gaps, it’s important to note that the size of those gaps can change throughout the year due to seasonal changes. The wood filler in those gaps isn’t elastic enough to adjust to these changes, and as a result, it can break up and look like kitty litter over time. This can make the gaps look even worse than they did before. In my opinion, it’s better to leave gaps open and honest instead of trying to fill them poorly with wood filler.

Trowel-filling and what does it mean? 

It involves spreading large quantities of filler over the entire area of a floor, allowing it to dry hard, and then sanding off everything that doesn’t fill a void. Trowel-filling can be beneficial in some cases, such as on new floors in climates where the boards don’t expand and contract very much through the seasons. In such cases, trowel-filling can help keep the finish contiguous. However, trowel-filling can be short-lived on older, already gappy floors in climates with season extremes. Within a year, the movement of the floor can break up the filler, leaving you with a finish that is no longer contiguous and a lot of loose fill between the boards.

Wood filler is not a replacement for new boards. 

It’s important to understand that wood filler is different from wood grain, and large areas of wood filler won’t blend in with the surrounding wood. Even if stained or finished to match the wood, it will still stand out and look like a big blob on your floor. When using filler for nail holes or chipped board corners, it can blend in with the grain pattern of the wood. However, larger voids will be noticeable and require multiple applications, as they shrink after each application. If you use too much filler and it takes hours to dry before sanding, you may be misusing it. Moreover, it’s better to sand clean any hollows or depressions in your floor instead of filling them with wood filler.

On the other hand, the floor finish is designed to be self-leveling and will flow and seek its own level on your floor, which means it will run through the gaps and down to the subfloor. As for using rope to fill up gaps, it’s important to remember that although it won’t crack and fall out like filler, it won’t blend in with the surrounding wood. You can use rope to fill up significant gaps and then apply filler on top to use less filler, but the stuffing will still eventually crack and fall out over time, even if there is less of it.


If you have small gaps or holes in your hardwood floors, it’s always best to try to fill them with actual wood. This is because wood doesn’t sink, and it shrinks and swells with the wood surrounding it. If you have holes, try using Plugs; they blend into the floor beautifully and are a fraction of the work of replacing a whole board.

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