Sealcoat (also called pavement sealer or asphalt sealer) is a protective coating applied to asphalt surfaces—most commonly parking lots and driveways—to help slow oxidation, block moisture intrusion, and improve the pavement’s appearance.
But “sealcoat” isn’t one single product. Performance depends heavily on what’s inside the mix—especially the binder system and the additives chosen for your surface, climate, and traffic.
What is a sealcoat, and what does it actually do?
Sealcoat is a thin, liquid-applied film that cures into a protective layer over asphalt. Its job is to reduce surface wear and help defend against common damage drivers like UV exposure, water penetration, and oxidation (which can accelerate raveling and cracking).
It’s important to keep expectations realistic: sealcoating is a preservation step, not a structural repair. If an asphalt surface has failed base layers, major alligator cracking, or severe depressions, repairs (patching, crack sealing, leveling) should come first—then sealcoat becomes the “shield” that helps protect the investment.
What are the main components in sealcoat?
Most modern sealcoat products share a core structure: binder + aggregates/fillers + liquid carrier + performance additives.
1) What is the binder in sealcoat?
The binder is the “glue” that forms the cured film and bonds the coating to the asphalt surface.
- Asphalt emulsion is one of the most common modern binders. It’s essentially fine asphalt particles dispersed in water with emulsifiers, creating a water-based sealer that cures as water evaporates.
- Coal-tar-based sealcoat has historically been used in some markets, but it has drawn major environmental and health scrutiny because it can be a significant source of PAHs (polycyclic aromatic hydrocarbons).
Why the binder matters: it influences adhesion, flexibility, chemical resistance, and how the surface holds up under traffic and weather.
2) What do mineral fillers and aggregates do?
Mineral fillers (and fine aggregates) are added to improve film strength, texture, and wear resistance. These may include materials like silica sand, limestone dust, slate dust, or other graded mineral powders.
Why they matter:
- Help the cured film resist scuffing and abrasion
- Improve traction (especially important on sloped lots, entrances, and high-turning zones)
- Influence viscosity so the product applies evenly and doesn’t “run” or settle poorly
3) Why is water included in sealcoat?
In many products (especially asphalt-emulsion systems), water is the carrier that keeps the mix workable for spraying/squeegeeing and helps distribute ingredients uniformly. As the sealcoat cures, water evaporates and the film hardens.
Why it matters: water content affects drying time, finish quality, and the risk of tracking (tire marks) if opened too early.
4) What additives are used in sealcoat—and what do they improve?
Additives are where sealcoat formulations get “tuned” for performance. Depending on the product, additives may include latex/polymer modifiers, rubberized components, UV stabilizers, rejuvenators, or other proprietary ingredients.
Common goals of additives:
- Better adhesion to the existing asphalt surface
- More flexibility to reduce premature cracking in the film
- Improved weathering/UV resistance
- Faster cure or better film formation in challenging conditions
- Enhanced durability in high-traffic areas (turn lanes, entrances, loading zones)
Are all sealcoats the same?
No—two sealcoats can look similar but behave very differently.
One major distinction is coal-tar-based vs. asphalt-based sealcoat:
- USGS notes coal-tar-based pavement sealcoat can be a potent source of PAH contamination in urban/suburban environments.
- Peer-reviewed research has reported PAH concentrations in coal-tar-based sealcoat can be dramatically higher than asphalt-based sealcoat (often cited at around orders of magnitude difference).
- EPA materials similarly discuss coal-tar sealcoat as a PAH-related stormwater pollution concern.
Practical takeaway: when you’re comparing bids or products, ask what binder system is being used and why it’s appropriate for your site.
How do you know what sealcoat is right for your pavement?
The “right” sealcoat is the one that matches your surface condition, traffic, and environmental exposure—and is installed using sound prep and application practices.
Key decision factors:
- Surface condition: If the lot has active cracking, oil-saturated areas, or failed patches, address those before coating.
- Traffic load: High-turn areas may need different mix design approaches or additional attention to reduce scuffing and wear.
- Environmental priorities: Many property owners and municipalities prefer asphalt-emulsion systems due to environmental concerns around coal-tar-based products.
What are best practices before and during sealcoat application?
Good results are less about “magic ingredients” and more about prep + timing + protection:
- Clean thoroughly (remove debris, dirt, vegetation, and contaminants).
- Treat oil spots (oil can prevent bonding).
- Repair first: crack seal, patch, and level where needed—then sealcoat.
- Protect adjacent areas and manage access until the film dries/hardens (a key theme in sealcoating BMP guidance).
FAQ
How long does sealcoat last?
It varies with traffic, climate, and surface condition. A well-prepped, properly applied sealer generally lasts longer than a rushed application on a dirty or damaged surface. Following BMP-style prep and protection steps is a major driver of lifespan.
Does sealcoat fix cracks?
No. Sealcoat is a surface coating. Cracks should be sealed (and failed areas repaired) before sealcoating for best results.
Is coal-tar sealcoat still used?
It exists in some markets, but its use has decreased in many areas due to environmental and health concerns tied to PAHs, as discussed by USGS and EPA.
What’s the biggest reason sealcoat fails early?
Poor prep and poor timing—coating over dirt, oil, moisture, or unresolved pavement distress—plus reopening traffic too soon. Sealcoating BMP guidance emphasizes protection of surrounding areas and proper drying/hardening time.
Conclusion
Sealcoat is a practical way to protect asphalt—when it’s chosen and installed correctly. The core ingredients (binder, mineral fillers, water, and performance additives) determine how well the coating bonds, cures, and withstands traffic and weather. And because not all sealcoats are the same—especially when comparing asphalt-emulsion systems and coal-tar-based products—knowing what’s in the mix helps you make a smarter, longer-lasting investment.
Why HSC Pavement Maintenance is Your Ideal Choice for Sealcoating?
Sealcoating delivers value only when the surface is properly evaluated, prepared, and protected during cure—details that are easy to overlook and expensive to redo. HSC Pavement Maintenance approaches sealcoating as part of a preservation plan, not a one-off cosmetic step, so repairs, crack sealing needs, and high-wear zones are addressed before a protective coat is applied.
Just as importantly, HSC’s team understands that different lots behave differently. Traffic patterns, turning stress, drainage, and surface condition all influence product selection and application approach. That jobsite-specific mindset helps property owners and facility managers get a finish that looks better, lasts longer, and supports a predictable maintenance cycle instead of surprise failures.
Ready to protect your asphalt? Contact HSC Pavement Maintenance.
If you’re planning sealcoating for a parking lot or driveway, reach out to HSC Pavement Maintenance for a site-informed recommendation and a quote built around the real condition of your pavement—not a one-size-fits-all approach.
