Three Ways To Apply Polyurethane Sealants

Polyurethane sealants are one of the most versatile types of sealants. They can be used on various surfaces such as masonry, bricks, concrete, wood, metal, plastic, masonry, aluminum, stucco, and many more. As a result, they are ideal for interior and exterior home applications as they are resistant to and flexible under any environment and weather conditions. While they are commonly used for sealing joints and cracks on the exterior of buildings, their uses extend to many interior areas.

Many users make a common mistake in conflating polyurethane sealants with polyurethane adhesive. They may have some common properties, but they are specifically designed for different reasons and should not be used for the same application. For example, the sealants are designed to provide a waterproof, air-tight seal to prevent moisture from entering openings, resulting in long-term structural damage. On the other hand, polyurethane adhesives are mainly used to reinforce and add strength to load-bearing structures in constructions. There are three common ways you can apply polyurethane sealants, with each method being designed for a unique and specific purpose and area of the home.


Spraying is designed to be more suited for applying on hard-to-reach surfaces and crevices such as chair spindles, shutter louvers, and flaking paints on various surfaces. This method is meant for going over areas that the wipe-on and brush-on methods cannot reach. Compared to the other two techniques, it is the trickiest to master and will require meticulous attention to avoid drips.

Therefore, it is wise to avoid extended sprays and use shorter bursts to avoid drips from forming as they will be difficult to remove afterward. To achieve an even finish, you will have to go over the surfaces more often than the brush-on and wipe-on methods. While spraying, you will have to ensure that the surrounding areas you do not want to coat are covered.

Wipe-On Application

The wipe-on application method is ideal for covering contoured, round, vertical surfaces such as star balusters, crown molding, and wainscoting. This is an alternative method to brushing, where it can create excess drips of polyurethane sealant caused by gravity that could make clean-up difficult on the spot. As a rule of thumb, one brush stroke is equivalent to four coats for a wipe-on method. Considering that wiping on dispenses a thinner application, you will require more coats for comprehensive and extensive coverage to give your workpiece an even finish. When using this method, here are some tips that you could use for a better application:

  • Using cloth folded to palm-size,  dip the sides of the fabric into the polyurethane sealant.
  • With even strokes and pressure, wipe the cloth on the surface in the direction following the grain
  • Remember to overlap the previous surface you have wiped to avoid gaps.

Brush-On Application

As compared to the wipe-on method, the brush-on application is ideal for surfaces that are broader, flatter, and horizontal in orientation. These could include furniture and floors, chairs, tabletops that lay flat where drips will be less likely to form. Traditionally, this method applies on a thicker coat and builds up faster than the other two methods mentioned. However, many new users face one common issue: unintentionally introducing bubbles during the application. You will remove excess product and unload the brush by slapping it against the polyurethane sealant can’s interior to combat this. Then, holding the brush vertically, drag it over the still wet coating. Here are some tips to help you achieve an even application:

  • Dip the brush into the sealant about one inch deep
  • Following the direction of the grain, apply the product with long and even pressured strokes
  • Run over the same area again to remove any excess drip
  • Overlap the previous site of the surface you have covered to ensure no gaps are left uncovered.

Check the surface, inspect any gaps and drips you might have missed, and rectify them.