Coal Tar vs. Asphalt Emulsion Sealer: The Honest Comparison

Both coal tar and asphalt emulsion sealers are water-based products designed for asphalt driveways. They look similar on the shelf and cost roughly the same. But their chemistry, performance, and safety profiles are dramatically different — and choosing between them is more consequential than most homeowners realize.

This comparison focuses exclusively on asphalt driveway sealers. If you have a concrete driveway, neither of these products is appropriate — see our best concrete driveway sealer reviews instead. For a broader comparison including other sealer types, see our complete asphalt sealer for driveways guide.

What Is Coal Tar Sealer?

Coal tar sealer is produced from the byproducts of coal carbonization — the same process used to make coke for steel manufacturing. The resulting coal tar is a complex mixture of hundreds of chemical compounds, including high concentrations of polycyclic aromatic hydrocarbons (PAHs).

In sealer form, coal tar is emulsified with water and additives to create a liquid coating that is applied to asphalt surfaces. When dry, it creates a hard, black protective film with exceptional resistance to gasoline, motor oil, antifreeze, and road salt. This chemical resistance is the primary reason coal tar dominated the asphalt sealing industry for decades.

What Is Asphalt Emulsion Sealer?

Asphalt emulsion sealer uses refined asphalt — the same petroleum-based binder that makes up the driveway itself — suspended in water as microscopic droplets. When the water evaporates, the asphalt deposits as a protective coating on the surface.

Because asphalt is chemically compatible with the asphalt pavement underneath, emulsion sealers bond well to asphalt driveways and provide good general protection against UV oxidation, water infiltration, and light chemical exposure. They contain dramatically lower concentrations of PAHs than coal tar — roughly 1,000 to 10,000 times lower by weight.

Detailed Comparison: 7 Key Performance Factors

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The Science Behind Coal Tar's Superior Chemical Resistance

To understand why coal tar outperforms asphalt emulsion on chemical resistance, you need to understand a basic principle of chemistry: like dissolves like. Petroleum-based solvents — gasoline, motor oil, diesel fuel, and brake fluid — tend to dissolve materials with similar chemical structures. Asphalt is itself a petroleum product, so petroleum solvents can, over time, penetrate and dissolve an asphalt emulsion sealer coating.

Coal tar, by contrast, is derived from coal — a completely different source material with a different molecular structure. Its principal components are aromatic ring compounds (benzene, naphthalene, anthracene, and related structures) that are far less soluble in the aliphatic petroleum compounds that make up gasoline and motor oil. This structural incompatibility is why coal tar forms a chemical barrier that petroleum solvents cannot easily penetrate.

The practical significance of this chemistry is most apparent in high-chemical-exposure situations: commercial parking lots where vehicles drip oil and antifreeze constantly, garages with vehicles that have active leaks, or driveways used by contractors who may bring diesel equipment onto the surface. In these scenarios, coal tar emulsion demonstrates a clear performance advantage that is measurable and significant. For a typical clean residential driveway with no active oil leaks, the chemical resistance advantage of coal tar over a quality asphalt emulsion is rarely meaningful in practice.

PAH Regulations by State: Where Coal Tar Is Restricted or Banned

The regulatory landscape for coal tar sealers continues to evolve as more jurisdictions act on the environmental and health evidence. Before purchasing any coal tar product, you must verify its current legal status in your specific location — fines for non-compliant application can be significant in some jurisdictions.

This list is not exhaustive and regulations change frequently. Always check with your local municipality or county health department before applying coal tar sealer. The trend is clearly toward broader restrictions as more jurisdictions act on the growing body of environmental research.

Application Differences: Does One Require More Skill Than the Other?

Both coal tar and asphalt emulsion sealers apply using the same basic method — squeegee, brush, or roller — and neither requires specialized equipment for residential DIY use. However, there are meaningful practical differences in application experience that affect the difficulty level, the risk of failure, and the precautions you need to take to protect yourself and surrounding surfaces.

Coal tar requires stricter weather conditions. Because coal tar emulsions are more sensitive to temperature extremes, the application window is narrower. Applying in temperatures above 90°F causes rapid skinning on the surface before the product has penetrated. Applying below 55°F risks inadequate curing. The optimal window for coal tar is 60–80°F with no direct intense sunlight — a narrower range than most asphalt emulsion products which tolerate 50–90°F.

Coal tar has a longer cure time before rain resistance. Most asphalt emulsion sealers achieve sufficient rain resistance within four to six hours. Coal tar typically requires a minimum of six to eight hours before the surface can withstand rainfall without washing away. This means the weather window for coal tar application needs to be more carefully managed.

Coal tar stains more aggressively and permanently. Asphalt emulsion is already a permanent stainer of concrete and other adjacent surfaces, but coal tar stains are even more difficult to remove and more visually obvious. Extra care in masking adjacent concrete, house foundations, and landscaping is essential when applying coal tar. Even minor splashing on concrete or brick can leave visible dark stains that resist removal.

Protective equipment is more important with coal tar. Both products require gloves and eye protection. Coal tar additionally warrants a vapor respirator during application and drying due to the significant volatile aromatic compound emissions. If you experience headaches or dizziness during application, move to a well-ventilated area immediately.

For the full product review of the top coal tar and asphalt emulsion sealers including Jetcoat, Latex-ite, and Gilsonite, see our complete best asphalt driveway sealer reviews.

One additional practical note on coal tar application: always stir the product thoroughly before use. Coal tar emulsions are heavy formulations and the dense components settle to the bottom of the bucket during shipping and storage. Inadequately mixed coal tar will produce an uneven application — thinner material at the top of the bucket applied first, followed by a thick, gummy layer from the unmixed sediment at the bottom. Use a paddle mixer attachment on a power drill for at least three to four minutes before pouring any product. This mixing step is less critical with asphalt emulsions but remains good practice for all sealer products that have been stored for more than a few days. For a full product comparison across the top brands in both categories — covering Jetcoat, Latex-ite, Gilsonite, and Black Jack — see our comprehensive best asphalt sealer guide.

Long-Term Durability: What the Research Shows

Independent testing of driveway sealer durability is more limited than manufacturer claims suggest, but the available data consistently supports a clear performance hierarchy. Coal tar emulsion products outperform standard asphalt emulsion products on most objective durability measures when tested under controlled laboratory conditions — particularly in abrasion resistance, water absorption reduction, and chemical resistance to petroleum solvents.

In real-world applications, however, the durability gap is often smaller than laboratory numbers suggest. Application quality is the dominant variable in field performance. A premium asphalt emulsion product applied correctly — meaning on a properly cleaned, degreased, and dried surface in two thin coats under appropriate weather conditions — will significantly outperform a coal tar product applied poorly over a contaminated or wet surface. The theoretical performance advantage of coal tar is meaningless if the application fails due to poor surface preparation.

The long-term trend in the industry is toward high-quality polymer-enhanced asphalt emulsions and acrylic polymer sealers that approach or match coal tar performance without the associated health and environmental concerns. Products like Jetcoat 10-Year represent the current ceiling of asphalt emulsion technology — the manufacturer warranty equals or exceeds what coal tar competitors offer. As polymer chemistry continues to advance, the performance case for coal tar is likely to weaken further over time.

For high-traffic commercial applications — parking lots, drive-through lanes, loading docks — coal tar still holds a measurable performance edge in abrasion resistance and chemical resistance that justifies its use where it is legally available. For residential driveways with normal vehicle traffic and no systematic petroleum spill exposure, the performance difference between premium asphalt emulsion and coal tar is negligible in practice, making the safety and environmental advantages of asphalt emulsion decisive for most homeowners.

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