How to Fix Sanding Mistakes: Over-Sanded Wood and Sanding Marks

By Cezar

While it might not seem like anything special, the fact that hardwood floors can be sanded is a huge advantage. Unlike almost any other flooring product, it allows you the freedom to repair damage and change the colour of your floor many times over its lifespan.

There are many reasons why you might need to sand your hardwood floors. Here are a few:

  • Refinishing
  • Changing the stain
  • Repairing damage
  • Removing paint or glue

While many homeowners take on sanding as a DIY project, it’s worth thinking at the beginning if you shouldn’t outsource it to a pro. Not only can the sanding equipment be unwieldy and the project messy, but sanding incorrectly can also introduce ugly marks. It’s also possible to over-sand your floors if you aren’t careful – wasting precious wood.

If you do want to press on yourself, however, this post should be an excellent introduction to how to sand a hardwood floor!

We’ll also discuss two of the most common problems homeowners run into with sanding and over-sanding, and how to fix sanding mistakes.

What You Need

Here is a basic list of the equipment you’ll need to sand your hardwood floors.

  • Floor Sander: These are powerful sanders made to allow you to cover your floor more quickly. A good rule of thumb is to get the most powerful sander that you feel comfortable using. A dustless or no-dust sander is a great choice if they are available, as using one is significantly cleaner.
  • Sandpaper: You’ll also need different types of sandpaper. A lower grit is used at the beginning of sanding and a higher grit towards the end – higher grit sandpapers are more abrasive. A normal sanding job might take sandpaper with grits of 60, 80, 100, and 120.
  • Detail Sander: An orbital sander is a good addition to your toolkit for sanding hard-to-reach areas and correcting mistakes.
  • PPE: Never start sanding without appropriate eye and respiration protection.

Sanding 101

Once you’ve finished preparing to sand, you can get started. Work one room at a time, always sanding with the grain. Use the orbital sander to sand any corners or other spots your main floor sander can’t reach. The first grain you use for sanding will be the lowest, probably around 60.

With each room, work from the lowest grade up to the highest.

While it might sound simple, sanding can be very tricky! It can be especially difficult to handle heavy-duty floor sanders.

If you run into trouble, we’re going to help you troubleshoot the two most common sanding issues below. Keep in mind, though, that you can usually save more time, money, and headache by talking to a pro!


Over-sanding isn’t a complicated problem. Sanding too much in a single place can leave your floor looking uneven or distorted. Usually, over-sanding occurs either because you lost your focus or because you were attempting to sand down a knot, bump, defect or just a particularly hard patch of wood – and went a little overboard.

The cure: The only cure is ultimately to sand down the rest of the wood to match. Here’s an easy way to do that:

  • Using a pencil, lightly shade the over-sanded wood and the surrounding area
  • Next, sand until the marks disappear – meaning the over-sanding area has been removed. It’s generally a good idea to pick a higher grit of sandpaper than the one that caused the problem. If you over-sanded using 80 grit, fix it using 100

Sanding Marks

Sanding incorrectly can introduce marks into the surface of your floor. The most common cause of this is not paying attention and accidentally sanding against or across the grain.

However, they can also be caused by a malfunctioning sander, so if you keep running into them despite your best efforts, it’s worth checking the unit.

Here is how to fix sanding mistakes:

The cure: The solution is to re-sand the wood until you’re happy with it. Small marks can ideally be dealt with using the next highest grit of sandpaper, but you’ll usually need one grit lower to remove the bad markings. A good technique can be to sand perpendicular to the direction of the marks – but be careful that you don’t introduce any new ones!


Sanding can be complicated, but it’s not impossible. With the right tools and some practice, most homeowners will be able to successfully complete their sanding projects. While a pro can complete a job without over-sanding or marks, you shouldn’t expect the same luck, especially on your first try. Using the guide above should allow you to easily fix sanding mistakes.

Once your floor has been sanded, apply your stain of choice along with a hardwood floor finish.