asphalt spray...it's oil based so it displaces moisture, it's not too thick like rubber, it dries as a smooth so no where for the dirt and salt to lodge.....An asphaltic based undercoating that provides excellent abrasion resistance, sound deadening and corrosion protection for use on car chassis and wheel wells.
KBS UnderCoat Features
- Asphalt based
- Sound Deadening
- Chip resistant
- Corrosion protection
- Easy to apply
- Excellent adhesion to metal
- Excellent adhesion to painted surfaces
- Dry To Touch In 1 Hour / Handle In 2 Hours
- Uniform appearance
- Spray, Brush, or Roll
....KBS UnderCoat produces a very tough, yet flexible film with excellent adhesion, and helps prevent road salt from eating away at your car's metal...No, the asphalt version does not contain rubber. KBS Coatings manufactures two distinct undercoating products: one formulated with asphalt/bitumen...the asphalt is more of a gritty texture...The asphalt coating will chip off in the off in the extreme cold....Prep the frame properly and then it’ll last....Asphalt undercoat should only be used on a brand new vehicle. Then there is nothing to trap, moisture or contaminants. Upon application underbelly in entirety should be decreased and washed/Rinsed. It'll be there for life if done properly....Asphalt-based Undercoating with self-healing properties...., for superior adhesion compared NOT an old-tech Rubberized formula.
Most of our customers use the KBS 3-Step System and then the KBS UnderCoat over that to give it a nice textured look.
The KBS UnderCoat does provide a degree of rust protection, but for the longest lasting rust protection, please choose the KBS 3-Step System.
Traditional Ziebart undercoating is an asphalt-based substance blended with rubberizing agents that dries into a thick, tar-like barrier.

Undercoat sprays have been dismissed as causing more problems than good - but those are the new "rubberized" undercoat sprays. The Old Skool Asphalt undercoat stays flexible yet seals and cures very strongly!! I know this because I have been spreading asphalt sealer on our 1/2 mile road!!
Asphalt undercoating has the benefit of being less expensive. They protect anywhere up to 5 years and dry to a Firm to Hard coating.
Asphalt Based Undercoating does require a thicker film thickness meaning you will have to apply more product to the surface to be protected then if you use a Wax Based Undercoating. Additionally, Asphalt based products require more surface preparation because they can actually seal in rust and moisture allowing it to continue to grow. Finally, Asphalt based products continue to dry out over time causing cracks in the coating surface.
So, if you are looking for a more cost effective undercoating that can protect your vehicle for up to 5 years but may require a little more surface preparation… then Asphalt Based Undercoating is what you need.

Stays pliable in extreme temps to prevent cracking & maintain integrity.... KBS UnderCoat produces a very tough, yet flexible film with excellent adhesion, and helps prevent road salt from eating away at your car's metal and fiberglass. KBS UnderCoat offers excellent adhesion to metal or painted surfaces. KBS UnderCoat provides moisture resistance & corrosion resistance, all in a black finish.
Remove any loose paint, rust, oil and grease.
I think I will use a twisted braided steel wire wheel on an angle grinder to really go to town on the frame rust - and remove the paint - to see how much rust is really there. I used a wire brush on a drill but that is not as powerful.... Better to be HONEST about how bad the frame is for rust.
acid-based conditioner designed to chemically etch bare metal substrates for improved adhesion while also converting light surface rust and providing protection. Excellent choice for after sandblasting, neutralizes flash rust and turns surface oxidation into iron phosphate. For best results, DTM Prep should be fully neutralized before primer application to ensure maximum adhesion. After fully dry, wipe with water, then dry again prior to coating. Ready for use,
I already had a big "repair kit" welded onto the frame and new rear trailing arm brackets welded on to the frame - and a metal "plate" welded over a frame hole....
I have been using phosphoric acid - which is the standard "rust prep" work - and I could do that again also. The problem with phosphoric acid is it also can "flash rust" - so ideally it turns BLACK as "iron phosphate." - I did just do a phosphoric acid treatment and at first it turned white - that is the phosphorus. Then almost all of it turned black! But even after the third spray there was some rust on top - a section on the top and I'm not sure if that was "flash rust" or if just didn't get enough phosphoric acid reaction.
So the only way to find out is wait for it to dry and then use the wire wheel to remove the layer of iron phosphate. And then remove any rust and then spray the asphalt seal over that...
Clean spray head immediately after use by turning can upside down and spraying until no more paint appears. If clogging occurs, remove spray head and clean with a fine wire. Replace carefully, pointing can and spray head away from you.
https://kbs-coatings.com/undercoat-directions
- Black automotive asphalt-based undercoating spray
- Heat resistant up to 300°F
- Applies easily with an aerosol spray can
- Maximum rust & corrosion resistance
- Excellent sound dampening
- Abrasion resistant
- Water, salt & chemical resistant
- Dry to the touch in 10 min, to handle in 6 hours
Suggested Uses for Seymour’s Asphalt Undercoat Undercarriage Coating Spray
Protect your vehicle. We’ve made it easy! Our Automotive Asphalt Undercoat Spray is ideal for:
- Panel & fender undersides
- Hoods & decks
- Trunk interiors
- Section repairs
- Weld joints
- Rust holes
- All chassis parts
| Asphalt-Based | 5 to 10 years | Commercial and heavy-duty vehicle services |


Can this be applied to rusty surfaces?