Coal Tar or Asphalt Emulsion Sealer: Which Is Right for an Anderson Driveway?

September 9, 2026

Both products make the same business-card-thick film; they differ in chemistry, in how they age through 42 freeze-thaw cycles a year, and in what the law says.

Two sealers, one job

Every driveway sealer is a film, roughly a business card thick, that keeps ultraviolet light, water and road salt off the asphalt binder underneath. The two families differ in what the film is made from. Coal-tar-based sealcoat typically contains 20 to 35 percent coal tar or coal-tar pitch, a byproduct of making coke for steel. Asphalt-based sealcoat is built on an asphalt emulsion, the same petroleum binder as the driveway itself suspended in water, usually with polymers and sand added.

Both go on the same way and need the same weather: pavement above roughly 50 degrees F and rising, and about 24 dry hours after the last coat. Neither one bridges a crack or firms up a soft base. The differences are chemistry, how the film ages, and the law.

What the PAH numbers say

The U.S. Geological Survey has measured both. Coal-tar sealcoat contains 35,000 to 200,000 milligrams of polycyclic aromatic hydrocarbons per kilogram, about 100 times the PAH content of used motor oil and about 1,000 times that of asphalt-based sealcoat. The Minnesota Pollution Control Agency notes that PAHs can be carcinogenic.

The film does not stay on the driveway. USGS found sealcoat abrades to a powder that rain, wind, tires and shoes carry into storm drains, streams and homes. House dust in apartments next to coal-tar-sealed lots carried PAH levels 25 times higher than dust near other pavement, and dust from sealed lots east of the Continental Divide, where coal tar is the traditional product, runs about 1,000 times higher in PAHs than in the West. In Anderson, what washes off a driveway heads for the storm drains and, downstream, the White River.

Where coal tar is banned, and where Indiana stands

Minnesota banned the sale and use of coal-tar sealants statewide effective January 1, 2014. A July 2016 tally by the Minnesota Pollution Control Agency also lists statewide bans in Washington and the District of Columbia, plus bans in Dane County, Wisconsin; Austin, Texas; Ann Arbor, Michigan; Winnetka and South Barrington, Illinois; and Westwood, Massachusetts. Austin's 2006 ban was followed by a 58 percent drop in PAH concentrations in Lady Bird Lake sediment. Home Depot, Lowe's and Ace Hardware stopped stocking coal-tar sealers for the do-it-yourself market.

Indiana has debated it and not acted. Senate Bill 168, which would have banned the sale and application of coal tar pavement products statewide, got a hearing in the Senate Environmental Affairs Committee in January 2018, and no vote was taken. No rule on sealer type appears in Anderson's zoning guide, so in Anderson the choice is still made job by job, by the property owner and the contractor.

Performance in a freeze-thaw town

Manufacturers that sell both products describe the tradeoffs in similar terms, and Anderson's climate tilts them.

• Fuel and oil: coal tar resists gasoline, diesel and motor-oil drips better. Asphalt-based sealer resists water-based cleaners and deicing salts well, and polymer-modified versions have narrowed the gap.
• Flexibility: coal tar cures hard and abrasion-resistant but grows brittle with age and, in one manufacturer's own words, is prone to cracking in freeze-thaw climates. Asphalt-based sealer stays flexible and moves with the pavement.
• Wear: asphalt-based sealer is described as wearing evenly with less flaking and peeling; coal tar starts glossy and very dark and holds strong resistance to ultraviolet light.
• Odor: asphalt-based sealer is low odor with no harsh fumes, which matters on a driveway ten feet from a bedroom window.
• Verdict from a neutral source: the Minnesota Stormwater Manual states that asphalt-based sealcoat, properly applied, performs as well as or better than coal tar at similar cost.

How to choose for your property

For a home driveway in Anderson, asphalt emulsion is the straightforward pick. The pavement moves through a regional average of 42 freeze-thaw cycles a year, brine rides in from State Road 9 and State Road 32 all winter, the runoff goes to the storm drain, and the product is easier to find and easier to be around. The case for coal tar narrows to surfaces that see constant fuel drips, such as a fueling apron or a truck yard, and that is a parking lot sealcoating conversation, not a residential one.

Either way, the coat count and sand load matter more than the chemistry. A single thinned coat of either product wears through long before two full coats of the other, which is why the cost page tells readers to compare scope before comparing price. Ask for the product name and its technical data sheet, the number of coats and whether sand is included, all in writing, before you line up bids for driveway sealcoating.

Questions to settle before the job

A written scope from an Anderson sealcoating contractor should answer five things: which product family and which product; how many coats and at what coverage rate; whether cracks are filled first and with what; how the pavement temperature will be checked on the morning of the job; and how many dry hours are required before cars return.

If the answer to the first question is coal tar, ask why. There are jobs where the fuel resistance earns it, but on a 1961 driveway in Edgewood or on the north side that gets salted tires and some 42 freeze-thaw swings a winter, a flexible, low-PAH film is the better match, and the one that would still be on the shelf if Indiana ever revisits a ban.

More from the blog

• One Coat or Two: How to Read a Sealcoating Quote in Anderson
• Pothole Repair in Anderson: Throw-and-Go Cold Patch vs Cut-and-Fill Hot Mix
• Driveway Ponding in Anderson: What to Do About Standing Water