The decision to have your asphalt pavement sealed is relatively easy. You have heard that sealcoating will help prolong the life of your pavement. You have seen freshly sealed pavements and noticed how rich the color appeared. Naturally, you want your pavement to have the best protection and look its most attractive, so you choose a reputable contractor to provide you with a quote for sealing your pavement. While he is inspecting your pavement, you tell him that you want him to apply a very thick layer of sealcoating to provide you with the maximum protection. You even offer to pay extra for the additional sealant. When he refuses your offer, you are confused. After all, the job will not take longer to complete; the only additional cost he would incur would be for the extra sealcoating. The reason for his refusal is simple — you have chosen a trustworthy, experienced contractor who knows that sealcoating should never be applied in one thick layer.
To understand why you do not want a thick layer of sealcoating applied to your pavement, it might be helpful to explain a little about sealants. Driveway sealcoating and Commerical Sealcoating is applied as a liquid that dries to form a hard shell; this is what protects your pavement. Because sealants start out as liquids, the moisture in the sealcoating must evaporate so that the sealant will cure properly and form the protective shell. If sealcoating is applied in a thin layer, evaporation can occur quickly. However, a thick layer prevents the moisture from evaporating properly, so it will take much longer for the sealant to cure evenly.
The problems do not end once the sealant finally dries. The prolonged drying time has allowed uneven curing, poor bonding with the pavement and product degradation. Virtually as soon as you open your pavement to traffic, the sealcoating will begin to flake or crack. Before you know it, your sealcoating has been worn away, leaving your pavement unprotected.
Customers sometimes think that the main drawback to sealcoating that has failed to dry thoroughly is that the sealant can be tracked. The real problem, however, is that the hard shell will not form. The shell is what protects the pavement from oil, gas and other automotive chemicals that break down asphalt pavement and leave it soft. The shell is what takes the punishment from deicing agents, melting ice, snowplows and rain. It also helps prevent tire scuffs and power steering marks. In simple terms, if the shell does not form, the sealcoating is not accomplishing any worthwhile function.
People sometimes wonder whether sprayers or squeegees are more likely to apply sealcoating too thickly. The truth is that in the hands of a novice, either tool can be used to apply the sealant too thickly. Conversely, in the hands of an experienced, qualified worker, either tool can be used to apply a thin layer of sealcoating.