Why Sealcoat? You have a large investment in your pavement. Replacing it is an expensive endeavor. Sealers are designed to protect and extend the life of your pavement; while at the same time enhancing its appearance. Sealcoating prevents the sun from oxidizing the asphaltic binder, it prevents damage caused by the elements, and protects the pavement from oil and gas that spills on the pavement. It reduces maintenance costs and extends the life of your pavement.
What wears sealer? Traffic, plowing and sanding all are factors.
When is a good time to start sealcoating my parking lot? The common mistake most people make is calling us after their pavement has cracked and in need of patching. To get the maximum life out of your pavement, a program should start within the first year. Your asphalt should be protected from its enemies, sun, oil and gas spills and water intrusion, as soon as possible. You wouldn't wait years before painting the wood on your house.
How soon after my parking lot is paved can I sealcoat it? As soon as the pavement rids itself of the surface oils. This is done through oxidation and rain. One way to check is to spread some water on the surface, if the water does not bead up and there are no rainbows caused by the surface, the asphalt is ready to be sealed. Depending on the weather this usually takes 6 to 8 weeks. Most people wait 6 months to a year before sealing.
Why are two thin coats of sealer better than one thick coat? Much like paint, sealer applied in 2 thin coats dries and cures much better than with 1 thick coat. Sealers are a water based product that dry and cure by evaporation of the water. A thin coat of sealer loses its water content much faster than a thick coat. A thick coat has a tendency to hold water and stay soft for a longer period of time. This could result in some tracking & premature wearing.
How many coats of sealer should be applied? Low traffic such as a typical home driveway, 1 coat is sufficient. Moderate traffic on a parking lot, 2 coats with a third coat on the entrance and exits. Heavy traffic 2 coats with a third coat on all travel lanes and roadways.
Does scuffing always occur? Scuffing is normal, even with additives, and usually occurs in the first month. Scuffing is usually worse on a hot day particularly when the temperatures go above 90 degrees. The best way to minimize scuffing is to try and not turn your car sharply when the lot is first opened up.
My unsealed driveway is getting tire/scuff marks. Will seal coating prevent this from happening? No, the seal coating will not help.
Why do some seal coating jobs fail to hold up? Surface preparation maybe the problem. Adhesion problems may occur due to pavement not being properly cleaned. The presence of dirt, or contaminants like oil, gas or grease will lead to flaking. Some asphalts even with primer applied are just too old, oxidized and/or polished for the sealer to bond properly. The sealer was not given enough time to cure before it was driven on. The contractor may have diluted the sealer with too much water or did not apply the recommended amount of the product. There is just too much traffic on the parking lot for the sealer to perform. A severe winter where a lot sand is used on the lot. The sealer was not applied in the proper weather conditions.
How long should my parking lot be closed off after it is sealed? If the sealer does not have an additive in it we recommend 24 hours. If the sealer has a fast drying additive of approximately 2%, then 12 hours. Factors that affect curing time include temperatures, humidity, and sun exposure.
I can't close my lot for 12 hours what can you do? Seal coating is a 7 day a week operation, maybe a Saturday or Sunday would work. We can seal the lot in sections so as not to disrupt traffic too much. There are some more expensive sealers designed to cure more quickly so you can open the lot up sooner.
Can you seal my lot at night? Seal coating at night is very risky. The weather conditions need to be ideal. It needs to be very warm with low humidity and a breeze certainly helps. You run the risk of the sealer not being dry in the morning, causing huge traffic and tracking problems. Typically if you seal at night the sealer will not be getting the proper curing time and may wear prematurely. The manufacturers also inform us that the sun is an important factor for the curing and longevity of the sealer.
Will the sealer fill depressions/holes and fill the cracks? No, sealer will not fill depressions or holes. If sealer is put on too thick it tends to flake off. Hot asphalt will be needed in these areas. Sealer does not work in the cracks. When it is dry it is not flexible enough to move when the cracks open and close during temperature changes. The sealer will just crumble in the cracks.
A vehicle just leaked on my newly sealed parking lot, what do I do? Sealer is oil and gas resistant. No products will protect your pavement from a spill that is left on the surface for an extended period of time. If cleaned up soon enough, there most likely will be a stain but the sealer will continue to protect the underlying asphalt from further damage. The best way to treat the spill is to apply Speedy Dry, cat litter or even dry sand to it immediately. Work it into the spill with a broom, shovel it up and dispose of it properly. If caught soon enough, power washing after the clean-up may remove some of the stain.
Can sealer be applied to concrete? No, pavement sealer does not bond well to concrete or cement surfaces. It will look good at first but it will peel and flake off becoming a constant maintenance problem and eye sore.
How often should I seal my asphalt? The typical asphalt parking lot is sealed every 2 to 3 years. The amount of traffic and the wearing is the deciding factor. Low traffic areas such as driveways need to be sealed less frequently than pavements with moderate or heavy traffic. Seal coating too frequently or over sealing is not good for your asphalt. Each time a lot is sealed it should be evaluated for wear patterns. Some areas may require only 1 coat while others may need 2 or 3 coats the next time you seal.
Why should I have sand in my sealer? Sand in the sealer gives a uniform texture that helps with traction and skid resistance. Sealer applied without sand in it tends to be more slippery. Sealers with sand in them tend to last longer and are safer to walk and drive on. Recommended sand loads are 4 to 6 lbs. of sand per gallon of the emulsion. Any more sand than that will result in a coating that will have poor flexibility, adhesion and lose some of its chemical resistance.
Why do some contractors put a latex additive in the sealer? The use of latex additives is very common these days. There are many additives each trying to improve the performance of the sealer in some way and help minimize scuff marks. Some examples are: Fast drying - additives that help speed up the drying and curing time of the sealer so it can be driven on sooner. Rubberizing Additives - to improve flexibility, toughness and durability Thickening Additives - which build the viscosity of seal coating diluted with large amounts of water.
Why two coats of sealer instead of one? Two coats of sealer will last longer than one. Over time you will have sealed more frequently with one coat and it will end up being more expensive. The labor costs for the mobilization, cleaning and surface preparation does not change for one coat versus two coats. The price difference between one coat and two coats is not half but the life expectancy is about half.
Why use a primer? Over time due to traffic and oxidation the surface aggregate becomes smooth and polished. Sealer does not bond well to a surface like it does to newer asphalt. For the seal coating to bond to this polished surface the sealer needs something to stick to. The right primer penetrates the smooth polished aggregate and allows the sealer to bond effectively. In older parking lots, unless there is a tremendous amount of traffic, we recommend applying PolyPrime to areas where the sealer wears first, the entrances, exits and travel lanes. The areas where the cars park wears very slowly so priming these areas is usually overkill.
What do I need to do to prepare for seal coating? Turn your sprinkler system off the day before the sealing is to be done. Turn it back on the day after the sealer has been done. Reschedule trash pickup, landscapers etc. Inform postman and newspaper delivery people. Newspaper people are notorious for driving right through the cones. Notify people who use the lot that it will be closed on that day and they will not be able to walk or park on the pavement. All vehicles, dumpsters, pallets etc. must be off of the paved area. To be safe put them at least 100 feet from the asphalt. While the cleaning process is going on there is a lot of dust flying through the air and an occasional gust of wind can blow the sealer quite a distance while it's being sprayed.
I have heard sealcoating my parking lot may yellow my white tile floors. There are two types of sealers, asphalt based and coal-tar based. Asphalt based sealers will not yellow tile floors. The coal-tar based sealer should not be used where there are white tile floors such as in grocery stores. The chances of foot traffic and shopping cart tires yellowing the floors are very likely.
How is sealer applied? Sealer can be applied by either spray or squeegee units. The spray units must be able to apply sealer with sand in it.
What causes white streaks in the sealcoating? It may be a problem with the sub-base itself. The limestone from the base maybe coming up with the water through pre-existing cracks in the pavement.
Why does the sealer dry gray? The sealer may have been applied under less than ideal weather conditions (high humidity, shade, or cooler temperatures). Usually the problem is temporary and the sealer darkens up after a few days.
What type of traffic paints can be applied to sealer? Water based traffic paints are preferred.
How soon can the striping be put on a sealed lot? If curing additives have been added to the sealer the striping can be done in the same day. The lines definitely look better if you can wait 24 hours or even a week.
Hopefully I have been able to answer some of your sealcoating questions.
Craig Swain is the president of New England Sealcoating Co., Inc., Hingham, Mass.