A seal coat is less expensive than resurfacing, and keeps water from penetrating the surface of the roadway. The two types of seal coats most commonly recommended by DPW are Fog Seals and Chip Seals. Fog seals are simply a sprayed-on liquid asphalt film that seals the pavement surface. Chip seals have a layer of small rocks placed over a thick coat of liquid asphalt. The rocks stick to the asphalt film and make a rougher surface that provides better traction to prevent skidding.
Chip sealed roads are lighter in color than fog sealed roads.
Fog seals and chip seals are placed on roads that still have enough structural strength to withstand the weight of traffic. For deteriorating roads that are losing this strength, more extensive resurfacing is required. Sun, heat, and vehicle loads can break down roads, but the biggest enemy of a road is water. When water gets underneath the pavement, the road becomes weaker. Small potholes grow into large potholes very quickly.