WATER. Blacktop is naturally porous. Water seeps into blacktop and deteriorates it. Freezing and thawing cycles during winter causes the water trapped inside to expand and contract, causing the blacktop to buckle. Sealing keeps water from seeping into blacktop.
SUN. Exposure to sun causes blacktop to crack, ravel and dry out. This lets water penetrate and cause damage.
CHEMICALS. Gasoline, lube oil, grease, road salts and antifreeze attack and soften blacktop. Sealing protects blacktop with a coating which is impervious to these chemicals.
BEAUTY. Sealing beautifies blacktop by giving the asphalt a rich, new-looking charcoal black appearance.