Can pet stains be sanded out of hardwood floors? (my recommendations)

Pet stains are the blight of homeowners all over the world that lift their carpets and find otherwise good hardwood floors. The problem becomes more apparent when they start sanding their flooring, and the pet stains are still visible or maybe now are even more noticeable. This question is a common one I get, and I’m finally writing the definitive answer here.

Can pet stains be sanded out of hardwood floors? Sanding hardwood floors only removes maybe 1-2mm of wood. The ammonia in pet stains penetrates deep into the timber. Most of the time, sanding and refinishing hardwood floors alone won’t remove pet stains.

However, there are some things that you can do to fix the problem. First, let’s explore and understand the issue a little more.

Why do pet stains penetrate so far into the surface, compared to other spills?

Ammonia is a funny chemical. You may know, from gardening experience, that urine on a compost heap will help it to decompose. This concept makes sense from the natural world. Animal urine has been helping organic matter to break down for millions of years.

Ammonia penetrates very deeply into the wood. Because of this fact, wood floor manufacturers use ammonia to “smoke” or “fume” oak to give it a darker appearance. That means that instead of staining, ammonia will soak in very deeply into the surface and change the color of the wood naturally. The great benefit of this is that even after sanding, it keeps its darkened appearance. Even after 2 or 3 sandings, it’s still darker, but at that point, it does start to lighten.

Another stain to look out for

Generally, when I’m facing deep dark stains, the culprit is the same, ammonia. However, sometimes there is another source.

Plant pot stains are equally as menacing. Lots of plant food products contain ammonia for the same reason discussed before; it breaks down dead plant matter which is great for creating fresh fertile soil.

The problem comes when plant the pot isn’t adequately sealed. The water carries the ammonia down the soil, out of the holes, and onto the wood floor. It usually goes unnoticed, which is how these problems arise. The spill has time to sit on the surface and soak into the wood.

This point is a perfect segway into my next, equally important topic.

How to prevent pet stains on wood floors

As I just mentioned, pet stains only cause real damage when they go noticed. If your pet has an accident on the floor, you see and clean it up fairly quickly; there is generally not too much of a problem here. It’s when the puddles go unnoticed that damage is being done.

One example that I see time and time again is rugs, especially shag-pile. Puddles and patches are far less visible in rugs, and they are often a preferred spot for pets to relieve themselves. The floor in the whole downstairs of the house can be spotless, yet you pull up the rug in the living room, and you see a multitude of stains in various darknesses.

In short, try to notice and clean up spills as soon as they happen. This way, the ammonia won’t have time to sink into the wood and cause real damage.

How to fix pet stains on wood floors

So what can be done about the stains on your floor? There are a few options:

Replace the affected boards.

Board replacement is the primary go-to choice of hardwood floor professionals. Instead of trying to sand out, or use chemicals to reduce or dampen the stain, they just cut those boards out and replace them. This method involves cutting inside the boards (away from the unaffected boards, and pulling the boards out.

It’s important not to damage the other boards around the affected area. Most floors are tongue and groove, so to get the new boards in, a handy technique is required.

The board has a tongue on one side and a groove on the other. Remove the strip of wood that forms the bottom of the groove. Removing this allows you to slip the tongue into the old flooring, then shift the board forward. Where the bottom of the old groove is missing, you now have the space to slip the board into place.

The only question is now, how to fasten that board in place. One way is to put a strip of expanding polyurethane adhesive along the line where the bottom of the groove was. The expanding glue will act as a new bottom groove.

The other way is to drive thin nails into the face of the boards, into the joists or battens. After this, punch the nails in with a hammer and nail punch. Fill the nail hole with an appropriate wood filler.

Use hydrogen peroxide to bleach the dark stains.

A method that is common in the discussion of pet stains is using hydrogen peroxide to bleach the stains. In my opinion, this is a very dubious method that has mixed results.

This method involves soaking the area with hydrogen peroxide, using a kitchen towel or rag. The cloth holds more on the surface for longer, allowing it to soak in and work. I have even seen people using an iron on a kitchen towel to use the heat to help penetrate.

This method works best when done toward the end of the sanding process. Maybe just before the final sand. The hydrogen peroxide tends to bleach the stains at the surface but not lower down. That means if you lighten the blemishes and then do a full sanding, you will reveal the spots again.

Stain it.

One option that many people go for is just staining over the floor. While this method doesn’t completely cover the imperfections up, it does go a long way toward hiding them.

Even contractors will do this for clients that can’t stretch the budget any further. There are preferred colors for staining over pet marks.

Duraseal Espresso is one stain I hear does very well in this regard. Unfortunately, Duraseal is a company that only sells to contractors. Duraseals sister company is Minwax. Minwax does sell to the public, and they have Minwax Provincial(Amazon Affiliate Link) which is also known for covering up a multitude of sins.

Does sanding and refinishing remove pet stains?

While I said earlier that sanding doesn’t remove pet stains “most of the time,” there is also that some of the time… If the stains are relatively shallow, removing the surface 1mm layer could take out those stains.

Here’s a great way to tell if this is possible. Put on your fresh 36 or 40 grit to start sanding the floor. Run over a stain, even if it’s just one side of the stain (if it’s a big stain). If the stain reduces in size significantly after running over it only once or twice, there is a good chance it may disappear if you run over it a couple more times.

If it doesn’t seem to make too much difference (sanding will always slightly reduce the size and darkness of the stain), then sanding deeper may not help.

Sacrifice a room of your house to make the rest better

Tacking on to the first suggestion, replacing the boards with new ones, maybe a better option. If you have a room in which you are happy to change the flooring, you can sacrifice that floor to make the rest of the house better.

Kitchens are a great candidate.

While kitchens may have food and spill stains, they generally won’t be as deep as pet stains. Tiles are much better suited for kitchens and bathrooms, so it may be worth upgrading your kitchen floor. That way, you will have boards to donate to the rest of the area.