Seal Coat 101
The sealcoat season is here.
As temperatures rise, plants bloom and your grass is getting greener, now is the time to begin to think about sealcoating your parking lot.
There is a ton of information and different opinions on what is the best way and the best material to seal your pavement with. Marketing programs will tell you why a brand of sealer is better than another. BlueSky recommends not focusing on the brand but on the application method and warranty provided by the installer.
Regardless of material used, BlueSky suggests 2-4 pounds of silica sand per gallon of sealant, this allows:
- Increased solids content in the liquid
- Helps decrease sun glare
- Helps increase wear life
- Creates a more skid/slip resistance
3 primary Types of Asphalt Sealers
Asphalt Emulsion Sealers
Asphalt emulsion sealers are asphalt-based and are popularly known as the environmentally-friendly alternative to protecting your driveway. However, it should also be noted that there are no known research or studies that have proven pollution or hazards are caused by paving one’s road with coal tar-based sealers. Asphalt-based sealants are better in terms of preserving air quality, smell better, prevent oxidization, and do not cause skin irritation.
The drawback to applying asphalt emulsion sealers though, is that it is prone to staining caused by oil or gas spillage. This sealer type also can only be applied between May and September for best cure time and are especially difficult to work on during the night time when the ambient temperature is at its lowest. The price of asphalt emulsion sealers is also extremely volatile due to the active demand for the product versus the limited amount of supply. Additionally, emulsion-based sealers have a large variance in product design, some have polymer modification some do not. Unlike Coal Tar there is no industry or ASTM standard for emulsion-based sealers.
Coal Tar Sealers
Coal tar is the most popular asphalt sealer in the market as it is weather-resistant and provides a long-lasting shiny finishing. Like its namesake suggests, coal tar sealers contain a substantial amount of coal tar mixed in with other polymers and strengthening additives. This water-based sealant is manufactured by baking coal. Coke is then extracted from the baking process which then becomes the main component of coal tar sealers and is the reason why it is resistant to petroleum-based chemicals. Coal Tar Sealers will be much more consistent from various manufactures due to meeting ASTM – 5727 standards, along with several FAA regulations.
Unfortunately, coal tar sealers are also believed to have a long-term detrimental impact on the health of local occupants as well as harm the environment. There are several states and local governments now banning the sale or use of Coal Tar Sealers as the sealer is believed to be contributing to water pollution and emits a harmful carcinogenic compound known as polycyclic aromatic hydrocarbon.
Acrylic sealers also do not contain any petroleum by products, which means that it is environmentally friendly as well. Another great benefit of this sealer is that it only must be reapplied every seven years as well, thereby contributing to savings in terms of maintenance costs.
Best practices for preparation and application.
BlueSky recommends the following steps be required for optimal results and best life cycle of sealcoating.
- Clean and properly prepared surface is the key to success
- All cracks should be sealed
- Damaged areas should be repaired
- Oil and chemical stains should be primed to assure adhesion of the new seal coat.
- First coat should be placed with squeegee or broom finish.
- This method helps assure that the sealer material is worked into the surface correctly.
- Second coat can be sprayed after the first coat is properly cured.
- Proper curing time is extremely important.
- Care should be taken to not allow traffic on it in between coats
- Spraying the second coat helps create a smooth and consistent finish for esthetics and longevity.
- Sealcoat materials can cure quickly in the ideal hot and dry conditions, cooler temps and higher humidity will increase curing time. BlueSky recommends that all sealcoat projects be allowed to cure for a minimum of 24-36 hours prior to any traffic be allowed back on it, or for reapplying line striping.
While there are numerous materials to be sold upon for your next sealcoating project, it is most important to partner with a contractor who cares about the application process and stands firmly behind their work.