Water popping is a straightforward concept, but if you are unfamiliar with it, there are a few key things to be aware of before you dive into it. We will cover what water popping is, why you may want to water pop, and a couple ways to water pop wood surfaces.
What is water popping?
Water popping or grain-popping consists of introducing clean water to an unfinished wood surface to open or "pop" the smooth and closed wood grain. Wood, by its nature, is hygroscopic and absorbs water. As wood absorbs water, the wood cells expand (open) and as the water evaporates, the expanded cells remain more open.
Water popping is often done as a prep step before staining or finishing, so it helps to be clear about what that means. A traditional stain mainly adds color at or near the surface of the wood, while a penetrating oil finish like Rubio Monocoat Oil Plus 2C soaks into the wood and bonds within the grain itself. Because water popping opens the grain, it is especially useful before a penetrating finish, helping the color absorb more deeply and evenly. If you are water popping wood before staining with a traditional stain, the same principle applies, though the effect is most pronounced with penetrating oils.
When to consider water popping?
To understand the need for water popping, we first need to understand the effects of sanding on wood. Wood flooring, or wood used in a furniture build project, typically gets sanded to create a flat, smooth, and blemish-free surface. Often, you start with a coarse grit sandpaper and go through progressively finer grits. As you sand to finer grits, the sanding closes the wood grain. Each time the grit is raised, the wood surface becomes smoother, shinier, and the grain becomes more closed.
Now that we understand what is happening on the wood surface, we can discuss some scenarios.
Product penetration
As the product category suggests, when applying a penetrating oil finish, like Oil Plus 2C, the product penetrates the wood grain. If the grain is closed too much, the product cannot penetrate as easily. If the product contains pigment, less product also means less pigment, resulting in a less intense color.
In this scenario, water popping helps to open the wood grain, allowing for more of the oil-based wood finish to penetrate, resulting in a more intense color.
Sanding imperfections
When a wood surface is finish-sanded, some sanding marks may remain. This could be caused by using too coarse a grit, improper sanding technique, or even damaged sanding tools. The sanding marks, when finished with a pigmented oil-based wood finish like Oil Plus 2C, often get highlighted by the pigment. Obviously, for aesthetic reasons, the visibility of sanding marks (aka sanding swirls or pigtails) is an undesirable situation.
Therefore, water popping minimizes the potential of visible sanding swirls.
Uneven sanding
If the sanding process is rushed or performed unevenly, there is a good chance that the grain is open in varying amounts across the surface, which will result in uneven absorption of the pigment/color of the oil-based wood finish.
In this scenario, water popping helps give a more consistent and even color appearance.
Blotchy appearance
Some wood species like Maple have a very uneven grain and absorb oil-based colors unevenly, resulting in a blotchy appearance.
Water popping reduces the naturally uneven and blotchy appearance in such wood species.
Water popping benefits
To summarize, water popping has the following benefits:
- More intense pigment penetration so you achieve deeper colors
- Avoids (or reduces) potential for visible sanding swirls
- More consistent and even color penetration with uneven finish sanding
- More consistent color penetration on naturally blotchy wood species
White Oak flooring board rough sanded to 80 grit, to demonstrate the effects of water popping.
Water popping vs. wood conditioner
Water popping and wood conditioner are sometimes confused because both affect how evenly wood takes color, but they work in opposite ways. Water popping uses only clean water to open and raise the grain, so a penetrating finish can absorb more deeply and color more intensely. A traditional pre-stain wood conditioner does the reverse: it partially seals the wood to limit absorption and reduce blotching, which also tends to lighten the final color.
With a penetrating oil finish like Oil Plus 2C, water popping is generally the better fit, because the goal is deeper, more even penetration rather than sealing the surface. Wood conditioners are more commonly paired with traditional surface stains on blotch-prone softwoods. For most hardwood floors and furniture finished with a penetrating oil, clean water is all you need.
How to water pop
Before you water pop, the wood should be finish-sanded but not burnished shut. For hardwood floors, that usually means sanding to about 100 to 120 grit before water popping. Furniture and millwork can be taken to about 100 to 150 grit but avoid sanding so fine that the grain closes up, since that makes it harder for both the water and the finish to absorb.
To get started, you need a clean water source. If you are uncertain about the quality of tap water, buy bottled water. When you begin, apply water generously to the wood surface but not excessively or leaving puddles. The goal is to wet the wood surface with water as evenly as possible.
Water is commonly applied to the wood surface by hand or using a sprayer.
How to water pop hardwood floors
Method 1
Fill a clean bucket with clean water. Dip a sponge or a rag/towel in the water and wet an area of wood evenly. Continue to treat the entire floor this way.
Method 2
Use a garden pump-up-style sprayer and fill it with clean water, completely pressurize the tank, spray an even mist of water on the wood surface, and immediately go over the sprayed area with a brushing tool, evening out the application of water. A so-called T-Bar outfitted with a waterborne applicator sleeve will do well for that on a hardwood floor. Continue treating the entire floor in this way.
Whichever method you use, remember to apply water to the entirety of the surface evenly, and without leaving any puddles. Pay particular attention not to allow water to puddle underneath the baseboards.
Water popping wood furniture or millwork
Here are some ways to water pop furniture or millwork:
Method 1
Fill a clean container with clean water. Dip a sponge or a rag in the water and wet the wood.
Method 2
Use a hand sprayer, fill it with clean water, spray an even mist of water onto the surface, and immediately go over the sprayed area with a brushing tool to even out the application of water. A brush or rag will be fine for that task.
Pay particular attention to any edges where water may drip down the side.
Allow to dry
After water popping, allow the wood surface to dry thoroughly; this usually takes 2-4 hours under favorable drying conditions. Cool temperatures or high relative humidity may lengthen the dry time.
Often, contractors may allow a water popped floor to dry overnight to avoid any potential problem; this is a safer approach. Remember to maintain good air movement through the area to facilitate good drying.
Additional considerations
In the case of wood floors, stay off the water popped floor until applying the finish, like Oil Plus 2C. With other water popped wood surfaces, do not bump or scuff the surface inadvertently.
Crushing the raised grain of water popped wood will consequently result in less color absorption.
Walk carefully on a water popped wood floor without pivoting on your shoes. You must carefully carry equipment onto the water popped floor to avoid problems with how the color/pigment will take.
Once the surface is water popped, there is no need for additional sanding. If you were to sand the raised grain smooth again, you would defeat the intent of the water popping.
When applying Oil Plus 2C on water popped wood, use a thick red pad (which is coarser than a thick white pad). The red pad will help knock down some of the raised grain during the oiling process and will result in a reasonably smooth surface.
Common water popping mistakes
Most water popping problems come down to a handful of avoidable mistakes:
- Over-wetting the surface or letting water pool under baseboards or along edges
- Crushing or scuffing the raised grain before you finish, which reduces how much color the wood absorbs
- Walking or pivoting on a water popped floor, or dragging equipment across it, before the finish goes on
- Finishing before the wood has dried back to its original moisture content
- Relying on water popping to hide poor or uneven sanding instead of improving the sanding itself
FAQs
How long should you wait after water popping before staining or finishing?
In favorable conditions, the surface usually needs about 2 to 4 hours to dry. Cool temperatures or high humidity can lengthen that, and many contractors let a water popped floor dry overnight to be safe. A moisture meter is the best way to confirm that the wood is back to its original moisture content before you finish.
Should you sand after water popping?
No. Sanding the raised grain smooth again defeats the purpose of water popping. Instead of sanding, gently knock down the raised grain while you finish, for example, by using a thick red pad when applying Rubio Monocoat Oil Plus 2C.
What grit should you sand to before water popping?
For hardwood floors, finish sanding to roughly 100 to 120 grit before water popping. Furniture and millwork can go to about 100 to 150 grit but avoid sanding so fine that the grain burnishes closed and resists absorption.
Is water popping the same as using a wood conditioner?
No. Water popping opens the grain so a penetrating finish absorbs more deeply, while a pre-stain wood conditioner partially seals the wood to limit absorption and reduce blotching. With a penetrating oil finish, water popping is usually the better choice.
Ready to finish?
Once your wood is water popped and fully dry, the prep is done and it is time to finish. Rubio Monocoat Oil Plus 2C is a penetrating, single-coat oil finish that bonds within the open grain for deep, even color in one application, which is exactly the result water popping sets up. Explore the available colors, grab a sample, and finish your floor or project with confidence.