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Bedford Sealcoating - sealing  NH driveways since 1996
Everything you need to know about asphalt sealer...
How does seal coat protects your pavement? 

Sealer is design to protect your driveway in the following three ways:

 Slows oxidation of asphalt caused by ultraviolet rays.
 As the driveway ages the asphalt binder becomes harder, and because of this hardening it becomes more and more brittle. Sealing your driveway regularly  will slow this process down and in some cases of newer driveways it can reverse it slightly.   

Creates barrier between the and the elements.
  Sealcoating protects the surface and fills in surface voids, reducing the pavement's exposure to oxygen, traffic and water, thus extending pavement life.   

Resists oil and gas spills
 This is especially important since gasoline and oil soften, or dissolve the binders in the asphalt . Coal tar sealers aren't soluble in gas or oil so they will help prevent damage caused by leaks or spills. Asphalt emulsion sealers, which  are soluble in gas or oil, usually include additives that enable them to resist such leaks, but they are not as effective as coal tar sealants. 
Oil-based sealer.
 An oil based sealer is a different application entirely to coal tar and asphalt emulsion. An oil based sealer penetrates and helps soften asphalt. A driveway with an oil base sealer application will have a shine to it after application that does not immediately dissapate. Once you use an oil base sealer on your driveway you cannot use either the asphalt emulsion or coal tar sealers for a very long time because of adhesion problems. We have not and do not use oil based sealers.

Asphalt emulsion
 The main ingredient in this sealer is a byproduct of the oil-refining process. Asphalt emulsion is much blacker in color. It is naturally compatible with the asphalt concrete, but by nature it is less resistant to oil and gasoline spills.  It has often been sited as the more environmentally friendly sealer than other types of sealer.  Studies have shown that rainwater runoff from driveways and parking lots sealed with coal tar sealers pollute the ground water.     In fact many states have banned the use of coal tar sealers entirely.

Refined coal tar emulsion 
Coal tar is a byproduct of the steel manufacturing process. After it has been refined, it is used as a sealer for both pavements and roofs. Coal tar emulsion is naturally resistant to oil and gasoline spills. Coal tar sealers are not as black as the asphalt emulsion sealers, but it's higher durability more than makes up for the slight difference in color. Coal tar emulsion sealer meets or exceeds all ASTM D5727, RP 355e, ASTM D 490, ASTM D 3320-74T, FAA P627,FAA P628, and FAAP631 specifications for coal tar pitch emulsion (CTPE) pavement sealer.

Make sure when choosing a sealer (or contractor) that it has an aggregate component (sand) in the sealcoat. This extends the life of the sealcoat and gives the driveway's surface more traction. This is even more important in the winter months when snow and ice can be an issue.
What types of sealer are there?
Our residential services area includes the following towns:

​Bedford, Amherst, Auburn, Bow, Candia, Chester, Derry, Dunbarton, Goffstown, Hollis, Hooksett, Hudson, Litchfield, Londonderry, Merrimack, Milford, Nashua, New Boston, Pelham, Salem, and Windham.