Coal tar emulsion driveway sealers generally work best on asphalt, delivering up to five years of protection against UV rays, water and petroleum-based products. However, many home and business owners choose asphalt emulsion driveway sealer due to the relative scarcity of coal tar emulsions and their more expensive price tags.
While asphalt emulsion driveway sealers generally last two to three years, they often fail to protect against UV radiation and degrade quickly when exposed to petroleum-based products. The upside of asphalt emulsion comes from its dark black color, which restores the original look of the asphalt, while higher-quality coal tar emulsion products tend toward turning the asphalt gray. For this reason, many choose to mix the two types of driveway sealers to ensure a better look while retaining many of the protective advantages of coal tar emulsion driveway sealers.