What is KBS UnderCoat Solvent Asphalt?
KBS UnderCoat Solvent Asphalt is a solvent based asphalt undercoating that seals wheel wells, frames, gas tanks, and floor pans against road salt and moisture while reducing road noise and vibration. KBS UnderCoat Solvent Asphalt dries to the touch in 60 minutes, reaches full cure in 2 to 4 hours, and bonds to bare metal, painted surfaces, and fiberglass without a separate primer.
100 to 120 sq ft
Coverage per Gallon
5 Sizes
Aerosol to 5 Gallon Pail
KBS UnderCoat Solvent Asphalt produces a tough, flexible matte black film with excellent adhesion, and helps prevent road salt from eating away at a vehicle's metal and fiberglass. The cured film stays flexible rather than brittle, which is what lets it absorb stone impact and flexing without cracking off the panel.
Sound control is the second reason owners reach for it. KBS UnderCoat Solvent Asphalt deadens road noise and vibration transmitted through floor pans, wheel wells, and quarter panels, so it does double duty on a restoration where cabin noise matters as much as corrosion.
KBS UnderCoat Solvent Asphalt stays paintable after it cures, so a color matched top coat can go over it when the undercarriage needs to match body color rather than stay black.
Manufactured in Valparaiso, Indiana and shipped factory direct the same day. Satisfaction guaranteed!
KBS UnderCoat Solvent Asphalt protects wheel wells, gas tanks, frames, quarter panels, fenders, undercarriages, hoods, decks, and floor pans. KBS UnderCoat Solvent Asphalt is built for the areas that take road salt, water, and stone impact, and one gallon covers 100 to 120 square feet of that surface in a sealed matte black film.
- Wheel Wells: The highest salt and stone exposure on the vehicle, and the most common failure point on an untreated undercarriage.
- Frames and Undercarriages: Seals frame rails and cross members against standing moisture and winter brine.
- Floor Pans: Blocks corrosion from below and cuts the road noise that comes straight through a bare pan.
- Gas Tanks: Protects the exterior of a steel tank where road spray collects.
- Quarter Panels and Fenders: Coats the inner surfaces that trap moisture behind the visible bodywork.
- Hoods: Adds sound and heat insulation to the underside of a hood panel.
- Decks: Seals trunk and deck areas that collect water around seams.
- Trailers and Equipment: Any steel surface underneath that sees weather and needs an economical, durable seal.
KBS UnderCoat Solvent Asphalt combines corrosion protection and sound deadening in one economical coating that sprays, brushes, or rolls on. KBS UnderCoat Solvent Asphalt needs no hardener and no primer, bonds to bare or painted metal and to cured RustSeal, and is dry to the touch in 60 minutes.
- Asphalt Based Formula: An asphalt binder that cures to a tough, flexible film rather than a brittle shell that chips off under impact.
- Sound Deadening: Reduces road noise and vibration carried through floor pans, wheel wells, and quarter panels.
- Chip Resistant: Flexes with the panel so gravel strikes dent the film instead of fracturing it.
- Corrosion Protection: Seals the surface against road salt, brine, and standing moisture.
- Excellent Adhesion to Metal: Bonds directly to clean bare steel with no separate primer step.
- Excellent Adhesion to Painted Surfaces: Goes over sound existing paint and over cured RustSeal without lifting it.
- Spray, Brush, or Roll: Applies through a Schutz style gun, a synthetic brush, or a synthetic roller, so no special equipment is required for small jobs.
- Uniform Matte Black Appearance: Lays down an even finish rather than a blotchy one, and stays paintable if a color coat is wanted later.
- Fast Handling: Dry to touch in 60 minutes and fully cured in 2 to 4 hours, so a job finishes in one session.
KBS UnderCoat Solvent Asphalt bonds to clean bare steel, previously painted metal, fiberglass, and cured RustSeal. Surfaces must be free of dirt, dust, oil, grease, loose paint, and loose rust before coating, and KBS Klean diluted 5 to 1 is the recommended cleaner for that prep step.
- Bare Steel
- Clean, dry bare metal takes KBS UnderCoat Solvent Asphalt directly with no primer. For maximum long term rust protection on bare metal, seal it with RustSeal first and coat over the cured RustSeal.
- Previously Painted Metal
- Sound, well adhered paint is a valid substrate. Remove any loose or flaking paint first, because the coating bonds to whatever is underneath it and a failing layer takes the coating with it.
- Fiberglass
- KBS UnderCoat Solvent Asphalt helps prevent road salt from attacking fiberglass panels and bodywork the same way it protects metal.
- Cured RustSeal
- KBS UnderCoat Solvent Asphalt has excellent adhesion to cured RustSeal, which makes it the finishing layer in the KBS 3-Step Rust Prevention System on a rusted undercarriage.
A gallon of KBS UnderCoat Solvent Asphalt covers 100 to 120 square feet, a quart covers 25 to 30 square feet, and a 5 gallon pail covers 500 to 600 square feet. Coverage varies with how smooth the surface is and how heavily the coating is applied, and rough or pitted metal consumes noticeably more material than smooth panels.
| Size | Typical Coverage |
|---|
| Aerosol | 16 to 20 sq. ft. |
| Quart (32 oz) | 25 to 30 sq. ft. |
| Gallon (128 oz) | 100 to 120 sq. ft. |
| 5 Gallon Pail (640 oz) | 500 to 600 sq. ft. |
Recoat window: allow about 10 minutes between light aerosol coats, or 2 hours between brushed and rolled coats.
How Many Coats of KBS UnderCoat Solvent Asphalt Are Needed?
Two light coats are the normal application. Light coats build an even film and cure predictably, while one heavy pass traps solvent underneath and slows the cure. On a brushed or rolled job the second coat goes on after 2 hours, and the surface needs a minimum of 24 hours to fully dry before it sees rain or moisture.
Pro Tip: Buy by the area, not by the vehicle. A typical full undercarriage on a passenger car runs well past a single quart, so a gallon at 100 to 120 square feet is the practical starting size for a whole underside, and the 5 gallon pail is the choice for trucks, trailers, and multi vehicle jobs.
Asphalt undercoating and rubberized undercoating differ in the binder that carries the coating: KBS UnderCoat Solvent Asphalt uses an asphalt binder, while a rubberized undercoating uses a synthetic rubber binder. Within the KBS solvent based line the working numbers are the same, so the real choice is binder character and the size range each formula is stocked in.
| | KBS UnderCoat Solvent Asphalt | KBS UnderCoat Solvent Rubberized |
|---|
| Binder | Asphalt based | Synthetic rubber based |
| Dry to touch | 60 minutes | 60 minutes |
| Full cure | 2 to 4 hours | 2 to 4 hours |
| Coverage per gallon | 100 to 120 sq. ft. | 100 to 120 sq. ft. |
| Sizes stocked | Aerosol through 5 gallon pail | Aerosol through 55 gallon drum |
| Paintable after cure | Yes | Yes |
The rubberized formula is the better choice on a job that needs more than 5 gallons, since it is stocked up to a 55 gallon drum, and for anyone who specifically wants a rubber binder underneath. For most single vehicle undercarriage work the two perform the same on the numbers that matter, and KBS UnderCoat Solvent Asphalt is the traditional asphalt option.
KBS UnderCoat Solvent Asphalt sprays, brushes, or rolls on after the surface is cleaned with KBS Klean diluted 5 to 1 and dried. Apply light coats, waiting about 10 minutes between aerosol coats or 2 hours between brushed and rolled coats, and expect the coating to be dry to the touch in 60 minutes.
- Step 1: Prepare the Surface
- Remove loose paint, rust, oil, and grease. Clean with KBS Klean diluted 5 to 1, allow the surface to dry thoroughly, and mask off the area so there is no overspray on the vehicle's finish.
- Step 2: Aerosol Application
- Shake the can at least 60 seconds after the agitator ball moves freely. Hold the can 10 to 12 inches from the surface and apply a uniform light coat, waiting about 10 minutes between coats.
- Step 3: Bulk Spray Application
- Spray quarts and gallons through the KBS Schutz Underseal Spray Gun or an auto body Schutz style applicator gun. Adjusting the gun pressure changes how textured the finished film is. Thinning is not usually needed, but KBS #1 Thinner will thin it if required.
- Step 4: Brush or Roll Application
- Mix thoroughly so any settled pigment is re-dispersed, then apply with a high quality synthetic brush or synthetic roller. The first coat is dry to the touch in 1 to 2 hours and the second coat goes on after 2 hours.
- Step 5: Cure and Top Coat
- Allow a minimum of 24 hours to fully dry. A top coat can go over a brushed or rolled application after 24 hours. Do not apply KBS UnderCoat Solvent Asphalt where it will be exposed to rain or moisture within 24 hours.
- Step 6: Clean Up
- Clean the spray gun immediately after use with KBS #1 Thinner, and wipe excess coating off unintended surfaces right away with KBS #1 Thinner.
What Temperature Should KBS UnderCoat Solvent Asphalt Be Applied At?
For best results apply KBS UnderCoat Solvent Asphalt between 70°F and 90°F with 50 percent or less relative humidity. Published dry and recoat times assume 70°F and 50 percent relative humidity, so cooler or more humid conditions extend every stage of the cure.
Safety: KBS UnderCoat Solvent Asphalt is a solvent based coating. Always work in a well ventilated area, always wear protective gloves and safety glasses, and heed all labeled warning and caution notices on the product. Do not apply KBS UnderCoat Solvent Asphalt to surfaces that come into direct contact with heat or high temperatures such as mufflers or exhaust components.
KBS UnderCoat Solvent Asphalt is the finishing layer of the KBS 3-Step Rust Prevention System, applied over cured RustSeal on a rusted undercarriage. Cleaning with KBS Klean comes first, RustSeal seals the rust second, and KBS UnderCoat Solvent Asphalt adds chip resistance and sound deadening on top.
- Step 1: KBS Klean
- Water based degreaser that strips grease, oil, and road film so the following coats bond properly. Dilute 5 to 1 for undercarriage prep.
- Step 2: RustSeal
- Single component rust encapsulating coating that seals rusted metal against moisture and oxygen without full rust removal.
- Step 3: KBS UnderCoat Solvent Asphalt
- Applied over the cured RustSeal to add chip resistance, sound deadening, and a sealed matte black finish.
See the KBS 3-Step System
Video Guides
The KBS how-to library covers rust prevention, prep, and coating application across the full product line.
KBS UnderCoat Directions and TDS
Full application directions, coverage table, cure times, and clean up for all three KBS UnderCoat formulas.
Read Article →
The KBS 3-Step Rust Prevention System
How KBS Klean, RustBlast, and RustSeal work together, and where UnderCoat fits as the finishing layer.
Read Article →
RustSeal Rust Encapsulating Coating
The coat that goes under KBS UnderCoat on rusted metal, and why the order matters on an undercarriage.
Read Article →
KBS Schutz Underseal Spray Gun
The applicator that sprays UnderCoat from a dome style quart can at 45 to 150 PSI, with a 48-inch cavity wand.
Read Article →
KBS UnderCoat Solvent Rubberized
The rubberized binder version of KBS UnderCoat, stocked from aerosol through a 55 gallon drum.
Read Article →
KBS Instructional Video Library
Free how-to videos covering rust prevention, surface prep, tank sealing, and coating application.
Read Article →
Have questions before you buy? Find answers to the most common KBS UnderCoat Solvent Asphalt questions below, or
order KBS UnderCoat now and get it shipped same day.
Asphalt undercoating uses an asphalt binder and rubberized undercoating uses a synthetic rubber binder. KBS sells both in the same solvent based line, and within that line the working numbers are identical: both dry to the touch in 60 minutes, reach full cure in 2 to 4 hours, cover 100 to 120 square feet per gallon, and stay paintable after cure. The practical difference is the size range. KBS UnderCoat Solvent Asphalt is stocked from aerosol through a 5 gallon pail, while the rubberized formula is stocked from aerosol through a 55 gallon drum.
Undercoating is worth it on any vehicle that sees road salt, gravel, or winter moisture, because a bare or lightly coated undercarriage stops being protected as soon as stone chips break through the original finish. KBS UnderCoat Solvent Asphalt adds a sealed, corrosion resistant film over wheel wells, frames, and floor pans, and it also reduces road noise and vibration. On a vehicle that only ever sees dry climates the corrosion payoff is smaller, and sound deadening becomes the main reason to apply it.
Asphalt undercoating is a corrosion and sound control coating for broad undercarriage areas such as wheel wells, frames, floor pans, and quarter panels. Rocker guard is a heavier textured chip coating aimed specifically at rocker panels and lower body panels that take constant stone impact. KBS UnderCoat Solvent Asphalt can be applied to rocker areas as well, and adjusting the pressure on the KBS Schutz Underseal Spray Gun changes how textured the finished film comes out.
The two real disadvantages are preparation and heat limits. Undercoating applied over loose rust, dirt, or oil seals the contamination in rather than stopping it, so the surface has to be cleaned with KBS Klean diluted 5 to 1 and dried thoroughly first. KBS UnderCoat Solvent Asphalt also must not be applied to parts that contact direct heat or high temperatures, such as mufflers and exhaust components, and it should not be exposed to rain or moisture within 24 hours of application.
KBS UnderCoat Solvent Asphalt is dry to the touch in 60 minutes and reaches full cure in 2 to 4 hours when sprayed. Brushed and rolled coats take longer: the first coat is dry to the touch in 1 to 2 hours, the second coat goes on after 2 hours, and a top coat can be applied after 24 hours. All published times are based on 70 degrees F and 50 percent relative humidity, so cooler or more humid conditions extend every stage.
KBS UnderCoat Solvent Asphalt sprays, brushes, or rolls on. Clean the surface with KBS Klean diluted 5 to 1, remove loose paint, rust, oil, and grease, let it dry, and mask off anything that should stay clean. From an aerosol, shake the can at least 60 seconds after the agitator ball moves freely, hold it 10 to 12 inches from the surface, and allow about 10 minutes between light coats. From a quart or gallon, spray it through the KBS Schutz Underseal Spray Gun or an auto body Schutz style applicator gun.
KBS UnderCoat Solvent Asphalt stays paintable after it cures, so a color matched top coat can be applied when the undercarriage needs to match body color rather than stay matte black. On a brushed or rolled application, allow 24 hours after the second coat before top coating. KBS UnderCoat Solvent Asphalt also bonds well over cured RustSeal, which is the recommended order when bare or rusted metal needs full rust protection underneath.
Do not apply KBS UnderCoat Solvent Asphalt to surfaces that come into direct contact with heat or high temperatures, such as mufflers, exhaust pipes, and other exhaust components. Do not apply it where it will be exposed to rain or moisture within 24 hours of application. Mask off the area before spraying so there is no overspray on the vehicle's finish, and always work in a well ventilated area with gloves and safety glasses.
A gallon of KBS UnderCoat Solvent Asphalt covers 100 to 120 square feet, a quart covers 25 to 30 square feet, an aerosol covers 16 to 20 square feet, and a 5 gallon pail covers 500 to 600 square feet. Coverage varies with how smooth the surface is and how heavily the coating is applied, and rough or pitted metal consumes more material than smooth panels.
Clean KBS UnderCoat Solvent Asphalt out of the spray gun immediately after spraying with KBS #1 Thinner. Wipe overspray or excess coating off unintended surfaces right away with KBS #1 Thinner while it is still wet, and discard the empty container properly. KBS #1 Thinner is also what thins the coating when thinning is needed, though the solvent based asphalt formula usually sprays without it.
