The Pros and Cons of Water Popping

Homeowners and commercial real estate developers love wood’s long-lasting beauty. Wood blends in with most types of décor and is easy to clean and maintain.

It’s environmentally safe, does not trap dust mites that can affect your indoor air quality, and it is comparable in price to other types of flooring such as stone, tile, and quality carpet.

However, the natural structure of wood – which looks appealing on the outside – is also what can cause problems from the inside. It all has to do with the relationship between wood and moisture. This is why water popping is such a vital, yet risky task when installing wood flooring.
how to make wood grain pop

What Is Water Popping?

Also called “grain popping” or “raising the grain”, water popping is a process that opens the grain in wood flooring; it involves adding water to the wood before you stain and finish it.

The Science Underlying Wood and Moisture

Wood is a hygroscopic material; it contains numerous cells that absorb water. In the tree, these cells fit together in groups of thin vertical passages like pipes. The cell wall contains a small amount of moisture, whereas the “hollow” part of the inner cell has room to hold and release moisture. The purpose of these cells and pipes is to collect and transfer water and nutrients from the roots of the tree to other parts.

After a tree is cut down, the green lumber is very moist, so the lumber must be kiln-dried to remove the excess moisture and make it ready for manufacturing.

However, the structure of the cells in the wood remains the same as before the tree was cut. Even long after cutting the tree, the cells in the wood absorb and release moisture from the environment. This moisture can be from relative humidity in the air, groundwater or water leaking from faulty plumbing.

As the humidity in a room goes up or down, the wood absorbs or releases moisture. This is a continuous exchange, even after you finish your flooring project.

Wood Moisture and Why You Need Water Popping

A wood flooring manufacturer buys kiln-dried lumber and cuts it down to size. Then, the lumber must be sanded down – often through several passes. During this process, the hardwood goes from being coarse to becoming fine and extremely smooth.

The sanding process closes the natural grain of the wood so the wood is no longer porous enough to accept stain. That’s because the tiny wood particles and sawdust get stuck inside some of the pores.

The sanding process begins with a coarse, low grit paper to flatten and clean the wood, then progressively finer grit sandpaper is applied to smooth the surface even more. Finer grits tighten the grain fibers, making the wood denser and less porous and penetrable.

The result is that the stain is not absorbed deeply into the wood, and most of the stain will be removed when wiped with a cloth.

Test your wood flooring with the most accurate and reliable wood moisture meter.

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Benefits of Water Popping

When water is added to the wood before staining it reopens the pores in the grain. It makes hardwood floors porous again so that hardwood flooring can be properly stained and finished.

This process has many benefits.

  • It allows the stain to be applied more evenly across the floor
  • It raises the wood fibers so the stain goes deep into the wood for a nice finish
  • It helps create a professional look and feel without any sanding marks
  • It makes the color stand out

It is important to use a precise quantity of water. Too much water can oversaturate the wood. This can cause the wood to swell in the short term. In the long term – as humidity decreases – the wood will release the excess moisture.

In addition, care must be taken to spread the water evenly across the surface of the floor. Uneven water distribution can cause your floor to show blotchy areas under the stain. If this happens, the only remedy is to re-sand the surface of the wood, which costs time and money.

To reduce this risk, many flooring professionals use a “T” bar. A “T” bar is shaped like a broom with a long handle that meets the end piece at a 90-degree angle. The end piece contains a straight-edged piece of rubber, like a window squeegee, that touches the floor and helps you distribute the water evenly.

Some use chemical sprayers to mist the floor with water. Some use a buffer with a soaked carpet pad. Still, others run a wet mop over the floor. Perhaps the most effective way, though time-consuming, is a bucket, a rag and getting down on your hands and knees.

No matter which method, it is fairly easy to do. This is especially true if you have experience with applying water-based finishes. The difference is that water popping employs clean water without chemicals, whereas finishes often contain substances that can hurt the wood.

It’s best to use purified or sterile water, not tap water. Tap water can contain excess chlorine and other chemicals that can react with the wood or the stain.

A standard plant watering can be used. Pour a 2-inch line of water, with the direction of the flooring grain. Then use the T-bar to even out the water.

After coating the whole floor, no matter which method you choose, let it stand and dry on its own for between two to four hours. At that point, the floor should be somewhat gritty, with it no longer having a smooth touch to it. This is the effect of the grain in the wood reopening.

Perhaps the most important step in the process is the close examination of the whole floor. You need to make sure the surface of the floor feels the same throughout. An area that is rougher or smoother than other areas may indicate that you did not apply the water uniformly.

Two Choices for One Outcome

water popping woodIf the surface of the floor is consistent, then the process was successful and stain can be applied.

However, if the floor surface feels different in spots, then it is necessary to repeat the process, or more likely re-sand the floor. Remember, if re-sanding is required, the water popping process is necessary afterward.

A Deeper Look at the Benefits

Stain More Evenly Across the Floor

Due to the application of various grits when sanding, the grain throughout the floor may not be uniform. When water popping is done correctly, the pores are opened throughout the flooring, allowing the stain to be more evenly applied.

Raises Wood Fibers Promoting Stain Penetration

Water popping causes the fiber in the wood to stand up, providing greater surface area for the stain to absorb and penetrate deep into the wood. Applying two coats of stain can give you an even nicer look.

Sustain a Professional Look and Feel without Any Sanding Marks

Even the best professionals can make a mistake. Sanding wood flooring can leave marks, however small, that are noticeable until after the wood is stained. When the grain is raised from water popping, any sanding marks blend in with the wood fibers, and when stained the marks won’t stand out.

The Wood Floor Stain Appears Darker and Richer

how to make wood grain stand outPerhaps the thing that stands out the most on a wood floor is the deep rich color. Water popping enables you to make your stain appear darker and richer. Darker and richer floors are noticeable, which many people admire. Be sure to ask to see the color you select on a sample of water-popped wood. Otherwise, the color you are shown you may not be what ends up on your floor.

Risks

Uneven Water

If you pour uneven amounts of water on different sections of the floor, you increase your risk of the wood absorbing various quantities of moisture. This can cause your floors to break down in the near or distant future, and your stain will look blotchy afterward.

Staining before the Floor is Dry

If you do not allow enough time for the floor to dry before staining the wood, you run the risk of the stain appearing blotchy. Drying time can differ by temperature, humidity and air circulation in the room. The lower the temperature, the higher the humidity, or less air circulating, the greater the amount of time you need for drying.


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Sensitivity to Scuff Marks

Once the wood has absorbed water it becomes soft and more susceptible to scuff marks. For this reason, you should not walk on the floor with any type of hard shoe or boot between the time of water popping and completing the staining process. Instead, wear only socks or slippers with very soft bottoms.

The Outcome Varies by Wood Type

The outcome from water popping can be incredible. You can have a professional floor that will last a lifetime. Visitors will commend you for a good job.

Nonetheless, your outcome can differ not only from the actual process but also by the type of wood. Each type of wood can differ in the amount of water needed for popping and the length of time to dry. Different types of wood also vary in how the color of the stain appears. These are the reasons why you ought to sample a piece of wood to “water pop” before committing to buying and installing the whole floor.

Test your wood flooring with the most accurate and reliable wood moisture meter.

Shop Orion Meters

What You Need Now – Moisture Measurement

Anyone can do it, but not everyone will do it right. To avoid the risks and maximize the benefits from water popping, it’s best to hire professionals who know how to measure moisture in the wood.

By looking at relative humidity at various places throughout the floor, you can get an accurate glimpse of how the moisture levels in the environment – now and later on – will affect the wood.

When the wood contains a low level of moisture that is at equilibrium with the environment and uniform throughout the floor, you can then seal it and apply the stain. An accurate wood moisture meter can help you lower or prevent the risks from water popping.

Last updated on June 30th, 2021

43 Comments

  1. kevin says:

    Can you water pop a floor if you are not staining it just putting 3 coat of clear polyurethane on it ?

    • Jason Spangler says:

      Kevin:

      Great question. I would recommend either talking directly with the polyurethane manufacturer and/or talking with the National Wood Flooring Association at nwfa.org. Good luck.

  2. Mike says:

    I use water-popping to open maple pores on violins I make. I wipe down the flamed maple with a damp microfiber cloth. Then, I stain it.

  3. Michelle says:

    Hi Tony,

    I have maple level 2 floors 3″. Original stain was orangey yellow. Added new hardwood to two rooms and tied into existing wood in hallway. I originally wanted just natural with clear poly, but opted for stain because of fear the tie-in areas would look better with stain. No one told us that it’s not recommended to stain maple 🙁

    Flooring company sanded everything, water popped and applied Early American minwax stain and three coats of water poly. Color looks blotchy, milky or cloudy in spots and just terribly uneven. The stairs look like I tried to sand the color off and got half way through the job (like a cheetah print). There were also several craftsmanship problems: footprints, drips, edges were darker, big dark circle where they started applying the stain on the machine, big sweeping “lanes” of very different coloring, wavy hallway, etc.

    Flooring company came back and sanded everything down again. For the most part it looks beautiful as-is, with a few spots where I can still see remnants of the stain, but you really have to look for it. I am fearful of trying stain again and we’ll just end up with the same blotchy brown floor. I do really like the natural color, but also not sure what the poly will do. Will it make it look yellow? They are using water-poly and I hear that won’t be yellow. But again I’m just not sure this crew has enough experience with maple (they mostly work on oak).

    Thoughts? Anything that should concern me if I stick with just a clear coat? Thank you so much for any advice you can give!!

  4. Patricia B says:

    Hi Tony, I am on my first project and just water popped the wood. Its a very heavy door (light-ish blond with black grains throughout ) This house was well built in the early 1900’s and has a lot of architectural wood detail. My question is should I sand over grain by hand when door dries or with the electric circular sander? My last pass was 180 grit. I’m using a water based polyurethane and going for a raw wood look. Also, does it matter how much time passes in-between water popping, sanding and finishing coat?

    Thank you.

    • Tony Morgan says:

      Thank you for your question. Water popping a door should be very similar to doing a floor. Generally, a circular sander is used for flooring because hand sanding would take much too long. Generally, a stain is applied 1-4 hours after the water popping is done and then at least three coats of polyurethane are applied when the stain has dried.

  5. I have laminate flooring it was here when we bought the house. The house is on a slab. Our floor is pulling a part there are places 1/4 how can we push those back? This flooring is no longer available and we don’t have any spare boards to replace it with. We have been told it is because of moisture from bein on a slab. This is a condo so you can’t get under to look at it. Thank you for any information.

    • Tony Morgan says:

      The most likely cause of this may have been that the flooring was installed when it had too much moisture in it, or, the concrete slab was too wet when the flooring was laid. These conditions would cause abnormal gaps (over 1/32nd to 1/16th in width). Due to it being a laminate to correct the gaps in this floor it may be necessary to replace the floor.

      If it were a solid wood floor, after stabilizing, this condition could possibly be corrected by using filler in the smaller gaps and slivers of wood for the larger gaps, then the entire floor would be sanded and recoated.

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