Blue Star Bluestar Flexible Asphalt Crack Filler, DIY - No Special Tools Needed, Fill Cracks in Asphalt Driveways and Parking Lots. 16 fl. oz. Bottle.

Why I reached for the Bluestar crack filler

A hairline split along my driveway had turned into a network of spider cracks, and one larger seam started throwing up fine grit every time it rained. I didn’t want to wheel out a kettle or buy a caulk gun just to tackle a few trouble spots. The Bluestar crack filler appealed because it promised a squeeze-bottle, no-tools approach, flexible performance in hot and cold weather, and the ability to handle wider gaps. I put a 16-ounce bottle to work across a mix of hairlines and a couple of 1/4–3/8 inch cracks to see how it would fare.

Packaging and application

The bottle arrives with a tapered nozzle that’s ready to cut to size. Tip: cut it at a shallow angle and start small—opening it too much makes it hard to control the flow. I shook the bottle thoroughly to re-suspend any settled solids, then worked in the shade on a dry, warm day.

No special tools are required, but a few simple add-ons help:
- Stiff brush or wire brush to clean the crack
- Shop vac or blower to remove dust and grit
- A 3-inch plastic scraper or putty knife for feathering edges
- Disposable gloves

The filler is pourable and self-leveling. I ran a steady bead along each crack and let it settle for a couple of minutes before lightly drawing a scraper over the surface to blend the edges with the surrounding asphalt.

Viscosity and how it behaves in the crack

This is a low-viscosity, asphalt-based emulsion that flows easily. That’s a double-edged sword. On the plus side, it capillaries into fine fissures and hairlines that thicker fillers simply bridge over. On the minus side, deep or wider voids will drink it up. Where my crack widened to around 3/8 inch and had an uneven bottom, the material sank and needed multiple lifts.

If you’re dealing with anything more than about 1/4 inch wide or 1/2 inch deep, plan to stage the repair:
- Pre-pack the void with dry, clean sand or a foam backer rod to bring the depth to roughly 1/2 inch.
- Apply a thin lift, let it skin and firm up, then add another.
- Avoid trying to fill a deep crack in one go; you’ll waste product and end up with a concave finish.

The label claims it can fill up to one-inch-wide cracks. It can—if you pre-fill and build in layers. Straight from the bottle into a wide, open gap, you’ll go through a lot of material and still see settling.

Dry and cure time

In warm (around 80°F) dry weather, the filler skinned over very quickly—within minutes. It reached a firm, foot-traffic-ready state in a couple of hours. Cure rate slows as the application gets thicker or the temperatures drop. For multi-pass filling, I waited until the previous lift was dry to the touch before topping up; this avoided slumping and yielded a smoother finish.

I wouldn’t apply if the pavement is damp or if rain is imminent. As with most asphalt emulsions, moisture in the crack will impair adhesion. Cleaning out loose dust, sand, or insect debris is equally important—any loose material becomes a bond breaker.

Flexibility and weather performance

After a hot week followed by cool nights and a soaking rain, the patches remained pliable and intact. There was no brittle cracking or edge lift along the hairlines I treated. The larger seam that had been moving slightly with temperature shifts stayed sealed, and the surface remained flexible instead of turning chalky. This is exactly what you want from a crack filler: enough give to accommodate seasonal movement without reopening.

Coverage and cost realities

This is a small bottle—16 ounces. Expect real-world coverage to vary drastically by crack width:
- Hairline cracks: You can get a surprising amount of linear footage because the material wicks in thinly.
- 1/8–1/4 inch cracks: I averaged roughly 12–18 feet per bottle, depending on depth and how much sinking I had to correct with second passes.
- 3/8 inch and larger: You’ll burn through the bottle quickly unless you pre-fill.

For small targeted repairs, the convenience is fantastic. For a driveway riddled with long, open joints, it’s not cost-effective. Once you start thinking in terms of dozens of feet of wider cracks, a larger pail of pourable filler or a caulk-tube product makes more financial sense.

Finish and appearance

The cured color is a dark black with a slightly richer tone than aged asphalt. On weathered driveways, the repair will look newer and darker until the surrounding surface catches up or you sealcoat over it. On a recently sealed driveway, the sheen mismatch can still be visible at certain angles—less a performance issue than a cosmetic one, but worth noting if you’re fussy about uniform appearance.

To improve the look, I feathered the edges with a plastic scraper right after each pour and avoided heavy overfill. Once cured, the patches sat flush and looked intentional rather than lumpy.

Durability so far

After several weeks of typical suburban abuse—sun, rain, a car tire turning across the repair—the filler has stayed bonded and flexible. Hairline cracks are fully sealed and haven’t telegraphed back through. The larger seam required an extra top-off a day later as the material settled; after that second pass, it’s held up without further sinking.

One lesson learned: cleanliness matters. In one spot where ants had kicked up fresh soil overnight, adhesion suffered until I re-cleaned and re-applied. If you’re trying to stop fine debris from working up through a crack, sealing it with a self-leveling filler like this works well, but only if the void is clean and dry at the moment of application.

What it’s best for

• Hairline to 1/4 inch cracks across driveways and parking pads
• Quick DIY touch-ups where pulling out extra tools would be overkill
• Sealing narrow, winding fissures that thicker pastes can’t penetrate
• Seasonal maintenance ahead of or after a sealcoat

Where it struggles

• Deep or wide voids unless you pre-fill and build in lifts
• Large jobs where the small bottle size becomes expensive
• Situations where a perfect color match to older asphalt is critical

Tips for success

• Cut the nozzle small and at an angle for control.
• Clean thoroughly: brush, vacuum or blow out, and make sure it’s dry.
• Pre-fill deep cracks with sand or backer rod.
• Apply in thin lifts; let each lift dry before topping up.
• Feather the edges with a plastic scraper for a flush finish.
• Work in warm, dry weather and avoid rain until fully cured.

Alternatives to consider

If you’re facing multiple long, open cracks, a caulk-tube asphalt sealant applied with a gun can be more efficient, and some thicker formulations are less prone to sinking. For alligatoring or wide, raveled sections, a patch compound or a more substantial pourable filler from a gallon jug may be better. Hot-pour rubberized sealants deliver excellent longevity, but they require more gear and prep.

Bottom line

The Bluestar crack filler is a genuinely easy, no-fuss way to seal small asphalt cracks and stop minor problems from growing. Its low viscosity is a feature, not a flaw, as long as you pair it with good prep and realistic expectations; it infiltrates micro-cracks that thicker products miss, cures quickly, and remains flexible through temperature swings. The trade-offs are coverage and cost on larger gaps, and a dark, “new” black that may stand out on older pavement.

Recommendation: I recommend this for homeowners tackling small to moderate crack repairs who value convenience and a clean finish. It shines for hairlines and narrow seams, quick touch-ups, and pre-sealcoat prep. If your driveway is dominated by deep or wide cracks, or you’re looking to cover long distances, choose a larger-format or thicker product instead and reserve this for the fine work it does best.