Both offer good protection; the biggest difference is in appearance. If you love the natural look of maple, apply a water-based (water-borne) polyurethane. They appear milky in the can, but go on clear and remain clear. They’ll slightly accent the character of your wood without giving it the amber tint of an oil-based poly. (However, some woods, like the oak shown, cry out for that amber tint.) Water-based finishes dry fast— most within two hours—so you can apply several coats in a day and use the room that night. They have minimal odor and clean up with water.

But water-based polys have their tradeoffs. They cost twice as much as oil-based polys. They won’t give wood the rich glow that oil-based polys impart; some even consider them cold looking.

Most water-based polys contain only 30 to 35 percent solids, compared with the 45 to 50 percent solids in oil-based products. Since these solids create the protective finish, you need to apply four coats, as opposed to two or three. And you may need to apply additional coats every two years or so.
There’s debate over which finish is harder, but some experts maintain that hardness isn’t necessarily a good attribute of a floor finish. You want a finish that will flex along with the floor. And a super-hard finish shows scratches more readily.

SURFACE FINISHES
These are the most popular choice and involve applying a stain to achieve a particular color, followed by a top coat of polyurethane or varnish to give a protective coat. Surface finishes are durable, they resist moisture, and are easy to maintain. There are four options for the top coat, and each has its own benefits:

OIL-BASED URETHANE is the most commonly used floor finish. Available in gloss, semi-gloss, and satin sheens, oil-based urethane is generally applied in two or three coats, with drying time of up to 8-15 hours for each coat. This type of finish emits fumes as it dries, so adequate ventilation is important. Clean up is accomplished with a solvent similar to paint thinner. An oil-based urethane finish ambers with age.

WATER-BASED URETHANE provides a clear, non-yellowing finish and produces fewer odors than other choices. This product dries quickly, and clean up can be accomplished with soap and water. Some manufacturers make available additives called "cross-linkers" that can be mixed into the water-based finishes for added durability.

MOISTURE-CURED URETHANE is a solvent-based polyurethane that is more durable and more moisture-resistant than other surface finishes. It is mostly used in commercial, high-traffic settings like stores or offices. This finish is available in a satin or gloss non-yellowing formula, as well as one that will take on an amber hue with age. This finish has a strong odor and its application is best left to the professional.

SHEEN
High gloss, low gloss, satin finish—your choice is a matter of personal preference. Keep in mind, however, that high gloss finishes show scuffs and scratches more readily than low gloss or satin finishes. High gloss finishes reflect more light and are typically used in more commercial or contemporary settings, while satin finishes reflect less light and are favored for more traditional settings.

EXTRA-DURABLE FINISHES
The latest trends in finishes include products designed to further extend the life of hardwood floors and make them more durable than ever. Some polyurethane finishes contain aluminum oxide to enhance the abrasion-resistance qualities of the floor. Some manufacturers report that this finish is 10 times more abrasion-resistant than other wood finishes, and are guaranteed for up to 25 years.

Swedish finishes are resin-based finishes that originated in Sweden. They form a tough film that is thin enough to allow the grain of the wood to be felt. Swedish finishes do not require waxing and can be recoated without sanding.