A fog seal is a very inexpensive way to add a little asphalt and a lot of protection to pavement surfaces. A light application of a diluted asphalt emulsion is sprayed on the pavement surface to protect against traffic and the environment. A timely fog seal in about the 6^th or 7^th year of service (or other time interval, depending upon the state of the original surface and local conditions) can effectively stop raveling for an additional 1 to 4 years, when it will be time to reapply another fog seal or other surface treatment. Fog seals can also be used as a color coating to blacken a pavement, or differentiate pavement lanes. Fog seals are used on both low- and high-volume roads to:

     Renew and protect old oxidized asphalt surfaces,
     Seal small cracks and surface void,
     Prevent damage to pavements placed in cold weather,
     Prevent raveling of chip seals,
     Prevent snow plow damage to chip seals,
     Blacken new chip seals,
     Prevent raveling of open-graded surfaces, and
     Maintain and delineate shoulders in high-volume roads.

Fog seals are generally applied to pavements displaying low to moderate-severity weathering or raveling, and used only where the existing surface is sufficiently porous to absorb the emulsion. They may also be applied to new surfaces, as added protection.