What Is Asphalt Sealer Made Of? | Ingredient Breakdown

Asphalt sealer is made from a water-based colloidal emulsion combining a binder (asphalt cement, coal tar, or petroleum distillate), mineral fillers, water, and performance-enhancing additives like polymers or latex.

One wrong assumption about driveway sealer can lead to poor adhesion, environmental fines, or a surface that wears thin in a single season. The fix for a failed sealcoat job starts long before the brush hits the pavement — it begins with knowing what is actually in the bucket. The binder type, the filler ratio, and the additive package determine everything: how long the coating lasts, whether it survives oil drips, and whether it is legal to use in your area.

What Are The Four Core Ingredients In Asphalt Sealer?

Every asphalt sealer contains four functional layers, even if the label lists them differently. The binder is the backbone — the material that sticks to the pavement and seals it against water and fuel. The fillers (clay, sand, or slate dust) give the coating body and texture. Water is the carrier that keeps the emulsion liquid enough to spread, and additives — polymers, latex, fast-dry agents — tune the sealer for specific jobs like high-traffic lots or cold-weather application.

The Binder Decides Everything: Coal Tar vs. Asphalt vs. Acrylic

The binder is what classifies the sealer and determines its toxicity, durability, and legality. Coal tar-based sealers use refined tar from steel and coal distillation — they contain 16 PAHs (polycyclic aromatic hydrocarbons) at concentrations roughly 1,300 times higher than asphalt-based alternatives, averaging 16,000 ppm total PAH versus roughly 50 ppm. Asphalt-based sealers use asphalt cement derived from petroleum refining, typically making up 20 to 35 percent of the final mix and carrying far lower health risks. Acrylic or paint-based sealers are polymer-only formulations, which are the most expensive option but offer high durability and no coal tar at all.

What Is The Typical Composition Of A Ready-To-Use Commercial Sealer?

When you buy a five-gallon pail off the shelf at a home center, the proportions are roughly the same across brands. The table below shows the composition of a common retail-grade asphalt sealer, based on the manufacturer’s safety data sheet.

Which Sealers Are Legal In Your Region — And Which Are Banned?

Coal tar-based sealers are restricted or banned in at least 27 jurisdictions across 10 states and Washington DC. New York State’s regulations specifically prohibit any sealer containing CAS#s 65996-93-2, 65996-89-6, or 8007-45-2, or product labels that list “RT-12” or “coal tar pitch volatiles.” If you live east of the Continental Divide, coal tar sealers were historically dominant because the steel mills that produced the raw material were nearby — but that legacy product is now illegal in many of those same areas. Our tested product roundup for the best asphalt sealer flags which formulas comply with each region’s rules; check the SDS from your contractor or store before buying. Asphalt-based alternatives contain roughly 50 ppm total PAH — 1,000 times less than coal tar — and are the mandatory replacement in restricted zones.

How To Mix Concentrated Sealer Correctly

Concentrated pavement sealers require adding three things before application: water for fluidity, silica sand at 10 to 20 percent to prevent tire tracking and improve grip, and polymer additives to anchor the sealer and increase the film thickness. The wrong sequence — or skipping the sand entirely — produces a thin, slippery coating that wears off within months. A section of the GemSeal technical guidance shows the standard mix design: add water first, then sand while mixing, and finish with polymer additive according to the manufacturer’s ratio. The sealer is ready when the mixture is uniform and flows without being runny — a good consistency is roughly the texture of thick latex paint.

Can You Tell The Difference Between Coal Tar And Asphalt Sealer By Eye?

Not reliably. Both products look nearly identical in the bucket — a dark, nearly black liquid with a similar viscosity. The only way to confirm which binder your sealer uses is to check the safety data sheet provided by the contractor or manufacturer. A quick trick: coal tar has a sharper, more chemical odor than asphalt emulsion, but odor alone is not enough to verify compliance with local laws. If you are in a regulated jurisdiction, the SDS is your only safe reference.

Are There Agricultural Or Bio-Based Asphalt Sealers?

Yes. A patented agricultural sealer (US6749677B2) uses soybean oil, alkyl esters of soybean oil, and d-limonene as the binder instead of petroleum or coal tar. These bio-based formulations exist primarily as specialty products and are less common on residential driveway jobs, but they represent a growing alternative for environmentally sensitive projects.

What Are The Biggest Mistakes When Choosing Or Applying Sealer?

The most common error is confusing coal tar with asphalt-based sealer and accidentally buying a restricted product. Contractors are required to supply an SDS — if they cannot or will not, that is a red flag. Skipping the sand addition is the second most frequent mistake; without silica sand, the sealer remains slippery when wet and wears unevenly. Over-applying polymer additives is another pitfall — the thicker film sounds better, but too much polymer makes the coating brittle and prone to cracking. And “green” labeled products are not automatically coal tar-free; you still need to check the CAS numbers on the SDS to confirm the binder type.

The single most useful decision you can make after reading this article: pull the SDS for whatever sealer you plan to buy and confirm the binder and CAS numbers. That one document tells you the composition, the legal status in your area, and the safety precautions for the job. Choosing the right binder type — and adding the correct amount of sand and polymer to the mix — is the difference between a driveway that holds up for five seasons and one that needs a redo next spring.