Typically, three coats — a sealer and two coats of finish — are used.

There are two main types of finishes for wood flooring — surface finishes and penetrating finishes.  And both have their advantages and disadvantages.  So before choosing one, figure out what best suits your needs.

Surface finishes for wood floors.

Today, most surface finishes are a blend of synthetic resins like urethane or polyurethane.  They form a protective coating that’s durable, water resistant and easy to maintain.

There are three varieties of urethane used to finish wood floors.  Water-based urethane is a relatively new product that’s sometimes mixed with a catalyst before it’s applied.  Water-based finishes dry more quickly than oil-modified urethane, which requires fewer coats.  And they’re less toxic than some other finishes.

But oil-modified urethane yellows with age and takes a while to dry.  Some people like the amber glow that older oil-modified urethane floors develop.

The third type of urethane, moisture-cured, dries quickly and is the most durable, but it‘s hard to apply.  Do-it-yourselfers should avoid moisture-cured urethane.

Polyurethane is extremely durable and stain resistant.  In fact, most basketball courts are finished with it.  It’s also less expensive than other finishes.

The other popular surface finish is conversion varnish.  Floors finished with conversion varnish are often referred to as Swedish finish hardwood floors.  Since it requires no waxing or buffing, a Swedish finish is very low maintenance.  And it’s almost as durable as polyurethane.

Because the varnish is flammable and contains formaldehyde, it’s restricted to professionals.  And you’ll probably need to vacate your home for a couple of days.  You may also need to air the house out once you move back in because the odor is quite strong.

A Swedish finish takes a long time to cure, so you should keep rugs off your floors for 60 days.  But once it’s cured, it’s one of the most attractive finishes for wood flooring.

Penetrating sealers for hardwood floors.

These solvent-based finished are applied to the wood flooring and then left on to penetrate the wood.  Then the excess is either buffed in or wiped off.  When color is added, penetrating finishes can also be used to stain the wood.

Many penetrating finishes contain tung or linseed oil and additives that promote hardness.   If there’s any damage to the floor, this finish is easy to repair.  Just rub on another coat.

Paste wax is one of the most popular choices because it’s easy to apply, inexpensive, and it lasts forever.  Thin coats of wax are applied to the wood floor, allowed to dry, and then buffed to a matte or satin sheen.

Choosing the right sheen for your wood flooring.

Most finishes are available in high gloss, semi gloss, satin, or matte.  Glossy finishes are harder to maintain and they show scratches and imperfections more.  Satin finishes are easier to keep looking good.