Fog seal
A fog seal is a light spray of diluted asphalt emulsion over an existing surface, with no aggregate added. It renews the surface, helps bind loose material and seals fine cracks. It is the thinnest and quickest of these treatments, and the surface can be slippery until it cures.
Fog sealing suits pavement that is aging and dry but structurally sound. It does little for cracks that are open or for surfaces that are already badly worn.
Slurry seal
A slurry seal is a mixture of asphalt emulsion, fine aggregate, water and additives, mixed in a truck and spread over the pavement in a thin layer. It fills minor surface voids, improves texture and gives the lot a uniform new look. Slurry mixes come in different aggregate sizes, chosen for the amount of traffic and the condition of the surface.
It lasts longer than a fog seal because it adds material, but it does not repair structural damage and does not close large cracks.
Chip seal
A chip seal is a layer of asphalt binder sprayed on the pavement and immediately covered with a single layer of aggregate chips, which are then rolled in. It is often called tar and chip, and it is a cost-effective way to renew roads and low-speed pavement.
The surface is rougher than other treatments and loose stone is common for a time afterward. Those traits make it less common on commercial parking lots where people walk and cars turn at low speed.
Sealcoating versus the other seal treatments
Parking lot sealcoating applies a thin protective coating, while fog, slurry and chip seals each change the surface in a different way. In practice, commercial parking lots in Phoenix are most often treated with sealcoating, with fog or slurry seals used in some conditions. Our sealcoating page covers the process.
Comparison
| Treatment | What it is | Best for | Watch for | | --- | --- | --- | --- | | Fog seal | Light emulsion spray, no aggregate | Aging, sound pavement | Slippery until cured; limited crack help | | Slurry seal | Emulsion, fine aggregate and water spread thin | Worn but sound pavement that needs texture and uniformity | Does not fix structural damage | | Chip seal | Binder with a layer of aggregate chips | Roads and low-speed pavement | Loose stone and rough surface | | Sealcoating | Thin protective surface coating | Sound parking lots | Not a repair; cracks need sealing first |
Which one does your lot need?
Start with condition. If the pavement is sound but aging, a surface treatment is the right category. If cracks are open, seal them first. If the surface is broken or the base has failed, no seal treatment will hold, and you need repair or mill and overlay. For the cost side, see our sealcoating cost guide.