Black Jack Elasto-Kool 700 White Elastomeric Roof Coating is a reflective roof coating designed to help protect compatible roof surfaces and reduce the amount of sunlight they absorb. The product may suit certain residential and commercial roof projects, but performance depends on the roof’s condition, preparation, weather, and correct application. Before buying, homeowners should confirm that the current product label lists their roof material, review the coverage and drying instructions, and check whether the roof has leaks or standing water that need to be addressed first.
What Is Black Jack Elasto-Kool 700?
Black Jack Elasto-Kool 700 is a white elastomeric roof coating sold by Gardner-Gibson. An elastomeric coating forms a flexible film after it dries. That flexibility allows the coating to expand and contract with normal temperature changes, while the white surface reflects more sunlight than many dark roofing materials.
It is a coating, not a replacement roof membrane or a general-purpose leak sealant. Its job is to add a protective, reflective layer to approved roof surfaces. It should not be treated as a way to repair structural damage, make an incompatible roof watertight, or eliminate persistent ponding water.
Product formulas, packaging, warranties, and approved uses can change. The container label and the manufacturer’s current technical data sheet are the controlling references for a specific purchase. In particular, users should verify the approved substrates, minimum application temperature, recommended number of coats, coverage, and cure time before starting.
How White Elastomeric Roof Coating Works
A white roof coating reflects a portion of incoming solar radiation instead of absorbing as much of it as a dark surface. The resulting reduction in roof-surface heating can help limit heat transfer into a building, although actual indoor temperature and energy savings depend on insulation, ventilation, climate, roof design, and air-conditioning use.
Elastomeric coatings are also designed to remain flexible as the roof expands in heat and contracts in cooler conditions. A continuous, properly applied film can help protect a sound roof surface from weather exposure. It does not make every roof “waterproof,” and no coating should be expected to compensate for failed flashing, loose seams, rotten decking, or leaks caused by a damaged roof assembly.
The U.S. Department of Energy describes cool roofs as surfaces that reflect more sunlight and absorb less heat than conventional roofs. A reflective coating may contribute to a cool-roof strategy, but the result varies by roof type and installation. The ENERGY STAR program’s roofing guidance also emphasizes solar reflectance and thermal emittance as relevant performance measures. A product’s current published data should be checked for any specific values or certification claims.
Roof Types and Compatibility
Compatibility is one of the most important checks when considering Black Jack Elasto-Kool 700. Roof coatings are not interchangeable: a product designed for one substrate may not adhere to another, and some surfaces require a primer or special preparation.
Depending on the current product instructions, Elasto-Kool 700 may be intended for certain existing roof surfaces such as metal or asphalt-based roofing. The precise approved list should be confirmed from the label and manufacturer documentation, rather than inferred from the word “elastomeric.” Coated or aged roofs can also present adhesion problems if their existing finish is chalky, peeling, oily, or incompatible.
Before purchasing, identify the roof material and condition. If the roof is made of a membrane, has a factory finish, or has been coated previously, ask the manufacturer or a qualified roofing professional whether the product is approved for that exact surface. Never assume a coating is appropriate for asphalt shingles, single-ply membranes, or other materials unless the label explicitly says so.
- Metal roofs: Check for rust, loose fasteners, failed seams, and existing paint or coating. Rust may require removal and a compatible corrosion-control treatment.
- Asphalt-based roofs: Confirm that the specific roof type is listed. Repair open seams and damaged areas with products approved for that system before coating.
- Previously coated roofs: Test adhesion and remove loose or flaking material. A new coating may not bond reliably to a failing old layer.
- Flat or low-slope roofs: Determine whether the roof has standing water. Many roof coatings are not intended for prolonged ponding, which can shorten service life or cause adhesion failure.
Benefits and Limitations
The main appeal of a white roof coating is its reflective finish. On a compatible roof, it can help reduce solar heat gain at the roof surface. The flexible coating may also provide an added weather-resistant layer when the roof is sound and the product is installed according to directions.
Other practical benefits may include easier maintenance compared with a full roof replacement and the ability to coat an existing surface. However, those advantages depend on the condition of the roof and the labor required for repairs and preparation. A coating is not automatically cheaper or more durable than replacement.
| Potential advantage | Important limitation |
|---|---|
| White reflective surface | Energy or comfort improvements vary with climate, insulation, and building design. |
| Flexible film | Flexibility does not bridge every crack or repair structural damage. |
| Can extend the service life of some roofs | It cannot restore a roof that has widespread deterioration or trapped moisture. |
| Applied over some existing roofing | Substrate approval and preparation requirements differ by roof system. |
Coverage and How Much to Buy
Coverage is not a single guaranteed figure for every roof. It varies with the product’s current directions, surface texture, porosity, application method, and the number of coats. Rough, weathered, or absorbent surfaces generally use more material than smooth, sound surfaces. The stated coverage on a container may also refer to one coat rather than a complete system.
Use the current label’s coverage rate to calculate the quantity. Measure the roof’s actual surface area, including slopes and sections that extend beyond the building footprint. Divide the total area by the label’s stated coverage per gallon for one coat, then account for the number of required coats and any extra material needed for edges, seams, or a porous surface.
For example, if the label indicates coverage of 100 square feet per gallon per coat and the project requires two coats over 1,000 square feet, the basic estimate would be 20 gallons before allowances for surface conditions and waste. This is only a calculation example, not a claim about Elasto-Kool 700’s current coverage. The label’s figures should always replace the example rate.
Buying too little can lead to a thin, uneven film or an incomplete second coat. Buying substantially more than needed may leave opened product that cannot be stored indefinitely. Check package size, shelf-life instructions, and return policies before purchasing.
Preparing the Roof Before Application
Good preparation is essential for adhesion and long-term performance. Coating over dirt, grease, loose material, or moisture can lead to peeling, blistering, or premature failure. Roof work also carries serious fall and electrical hazards; work should be postponed in unsafe conditions and left to trained professionals when access is difficult.
- Inspect the roof: Look for leaks, soft areas, open seams, damaged flashing, loose fasteners, rust, and signs of trapped moisture. Repair underlying problems before coating.
- Remove debris: Clear leaves and dirt, then clean the surface using a method permitted by the label. Avoid damaging the roof or directing water beneath seams.
- Let the roof dry: Do not coat a wet surface. Follow the product instructions for acceptable surface conditions and weather.
- Repair defects: Use compatible repair products for seams, penetrations, and localized damage. Allow repairs to cure as directed.
- Check adhesion: On a previously coated surface, a small test area can help reveal bonding problems. Follow manufacturer guidance on testing.
Roof coatings can trap moisture if applied over a wet or deteriorated roof. If there is uncertainty about the roof assembly, a roofer should inspect it before a coating is applied. Covering concealed damage can make later repairs more difficult and expensive.
How to Apply Black Jack Elasto-Kool 700
Application details should come from the current container label and technical data sheet. These instructions govern temperature limits, weather windows, tools, coat thickness, drying time, and whether the product needs stirring or a particular application method. Do not rely on instructions for a different Black Jack coating, since products in the same brand can have different requirements.
In general, application should begin only after the roof is properly prepared and dry, and when the forecast allows the coating to dry or cure without rain, dew, or freezing conditions. Apply an even coat at the label’s specified rate. If a second coat is required, observe the stated recoat interval and follow any direction about application direction between coats.
Use appropriate protective equipment and take precautions against spills and splashes. Avoid coating roof drains, vents, or other components in a way that obstructs their function. Keep people off the coated surface until the manufacturer says it is safe to walk on. Do not apply the coating outside the temperature, humidity, or weather limits stated on the package.
Common Mistakes to Avoid
- Using the coating as a leak repair: Active leaks need diagnosis and repair before the roof is coated.
- Ignoring standing water: Persistent ponding may indicate drainage or structural issues and can be incompatible with the coating system.
- Applying too thinly: Stretching a container beyond its labeled coverage can reduce film build and performance.
- Skipping surface preparation: Dirt, rust, moisture, and loose old coating can undermine adhesion.
- Coating an unapproved material: Confirm the exact roof substrate and any primer requirements.
- Assuming the coating guarantees energy savings: Reflectivity can affect roof heating, but building-level savings depend on multiple factors.
Maintenance and Expected Performance
After the coating cures, periodic roof inspections can identify punctures, peeling, debris buildup, blocked drains, or new damage. Inspection frequency depends on the roof and local weather, but checks after severe storms and as part of routine roof maintenance are prudent. Repairs should use products compatible with the coating system.
Service life depends on installation quality, exposure, roof movement, drainage, and maintenance. A warranty, if offered for the product, may include conditions relating to surface preparation, application rate, number of coats, and eligible roof types. Read the warranty terms before beginning; the label’s warranty period should not be treated as a promise that every roof will perform for that length of time without maintenance.
Where to Find Product Details and Reliable Guidance
For the most accurate information, consult the Gardner-Gibson manufacturer website and the label on the exact container being purchased. The company’s current product page or technical data sheet can clarify approved surfaces, coverage, application conditions, and warranty terms. Retailer listings can be useful for availability, but may contain outdated specifications.
For broader context on reflective roofing, the U.S. Department of Energy’s cool-roof guidance explains how reflective roofs may reduce heat absorption and why results vary by building. The ENERGY STAR roof products information offers additional background on roof reflectance and product performance. These sources explain cool-roof principles; they do not substitute for product-specific installation instructions.
Quick Buying Checklist
- Confirm that Black Jack Elasto-Kool 700 is approved for the exact roof material.
- Check whether the roof has active leaks, ponding water, rust, or damaged decking.
- Read the current label for coverage, number of coats, and drying conditions.
- Calculate material using actual roof area and the required application rate.
- Review primer, repair, safety, and warranty requirements before starting.