Water popping is a process that includes adding a layer to water to your sanded wood before staining. Waterpopping is done with a few different application methods- a wet towel can be rubbed over the floor, applied with a mop or sprayed on with a mister. The water layer needs to be applied evenly to ensure the stain will not be blotchy. Water popping is also referred to as grain popping, popping the grain and other similar variations.
The water popping process reopens the graining and pores in the wood that was flattened during the sanding process. Wood is hydroscopic so it will retain and expel water based on the moisture in the environment. When water is applied to the wood flooring the pores swell up. The stain is able to better penetrate the floor. The end result is a deeper and richer stain, especially when the stain is a dark color. Oak is a low oil wood and water popping works great on this species.
Water popping is only done with certain wood species and certain stain colors. When a light color or natural color stain is being used water popping is not advised. The species of wood is also something to consider. Maple will be even more blotchy with water popping.
Exotic woods are less commonly stained because of the natural beauty and coloring of the wood. Water popping is not needed when keeping the wood natural. Many of the exotic woods have a high oil content and should not be water popped. Depending on the finish and wood species some exotics have to be rubbed down with a denatured alcohol to ensure adhesion due to the oil content.
Never apply mineral spirits or paint thinner as a water popping agent. These will leave a residue on your floor and can also damage the wood. The water popping leaves the wood ready for stain and leaves no residue. The mineral spirits can also affect adhesion due to the residue.