Black stains that appear on wood can be concerning, and many people aren’t sure where the stains have come from. Black stains can be caused by a variety of things, from a reaction to a wood finishing product to mold or iron oxide. But what’s the best way to remove these stains?
Black stains caused by mold or iron oxide can be removed by using sandpaper to sand out the stain and refinishing the wood, or by using a bleach solution. Bleach works best for mold. You can tell if the stain is mold by the smell, texture, and whether it has spread at all.
Let’s take a closer look at black stains in wood, including what causes them in the first place, how you can tell the difference between different stain causes, and the best method to get rid of them. We’ll also consider when it’s time to call a professional for help.
What Causes Black Stains on Wood?
While white stains on wood can be caused by water, black stains are a different story. Sometimes, they’re caused by chemical reactions with certain types of wood finishes, but the most common causes are mold and iron oxide.
Mold may form when the wood has had prolonged exposure to moisture and begins to rot. This can happen from moisture creeping up from below the surface in floors, exposure to weather, or spills that aren’t properly mopped up.
Iron oxide stains are caused in a similar way, developing from either prolonged exposure to moisture or metal. Iron oxide reacts with the wood and stains it the same color as mold does.
Mold vs. Iron Oxide: How to Tell the Difference
There are a few ways you can tell the difference between stains caused by mold and iron oxide. Here’s what to look for:
The Texture
Iron oxide stains are usually smooth and don’t have much of a texture to them. Mold, however, is usually fuzzy and almost has the appearance of fur or hair.
The Smell
Iron oxide stains usually don’t smell, so if you’re close to it, you may not notice an odor. Mold, however, has a naturally musty smell. If you noticed the stains in the first place because you could smell something coming from the wood, there’s a good chance that the stain is due to mold.
The Spread
If there’s an iron oxide stain, it tends to remain the same size and stay in one place. Mold, however, will spread pretty quickly. If it’s changing shape and moving over the wood, it’s mold.
Supplies You’ll Need
You’ll need to gather the following supplies before you go ahead and try to remove the black stain from the wood. Exact supplies may depend on the severity of the stain and your preferred removal method:
- Sandpaper of various grits (which you can buy on Amazon)
- A vacuum cleaner
- Bleach (also on Amazon)
- Microfiber cleaning cloths (on Amazon)
- Safety goggles and gloves
It’s important not to skip the safety goggles and gloves. If you’re dealing with mold, it’s best to avoid contact with it, and using the correct safety equipment means it won’t cause any problems for you.
How to Remove Black Wood Stains
Here are some ideas for how to remove black wood stains. Make sure to follow the steps carefully and take safety precautions, as mold can cause issues with health, especially if you have a pre-existing respiratory condition.
Sanding
The first thing you can do is sand the wood to get rid of the stain. This may be necessary if it’s gone very deep.
- Start by identifying the affected area.
- Use a coarse-grit sandpaper (60-80 grit) to sand the affected area. Sand in the direction of the grain and avoid uneven surfaces.
- Check the progress frequently to ensure that you’re sanding evenly and not removing more wood than necessary.
- Once the black stain has been removed, switch to a finer grit sandpaper (100-120 grit) to smooth the surface of the wood.
- Continue sanding with increasingly finer grits (150-180 grit) until the surface is smooth.
- Use a vacuum to remove the sawdust created by the sanding process.
- Finally, wipe the surface of the wood with a microfiber cloth to remove any remaining dust.
Bleaching
Although, as a general rule, you shouldn’t use bleach on wood, it can be important to do so if there’s mold — and it may be the only thing that works.
- Identify the affected area.
- Mix three parts water to one part bleach and wipe it onto the surface with a cloth.
- Leave it for a few minutes before rinsing it off and drying the area.
- If there’s still mold, you can repeat the steps and leave it on for a little longer.
Professional Help
If neither of these methods works for removing the stain, then you might need to seek professional help. This can happen if mold has gone very deep into the wood, and you shouldn’t be tempted to resort to more abrasive substances that might only make things worse. Instead, try these DIY methods and then contact a trusted professional if it doesn’t work.
Black stains on wood don’t have to be the end of the world, although they can look pretty bad. It’s possible to sand or bleach the stain out, and if that doesn’t work, a professional should be able to do the job for you.