Will Cavity Wax Stop Rust in Rusty Cavities?

Yes. Cavity Coater goes right over lightly rusted metal inside rocker panels, frame rails, doors and other enclosed cavities, and it stops that rust from getting worse. Knock off any loose, scaly rust you can reach, make sure the surface is dry, and spray. Cavity Coater wicks into the seams, displaces water on contact, and seals the metal off from moisture and road salt.

Cavity Coater on Rusty Metal: Quick Facts

Goes over: bare, painted, or lightly rusted metal

Prep: knock off loose, scaly rust; clean grease or oil with KBS Klean

Surface: must be dry

Salt spray: more than 4,000 hours, ASTM B-117 on steel

Film: one coat, 1 mil dry

Cold weather: no cracking or flaking down to minus 60 degrees F

The surface must be dry. That is the one hard requirement. Rust can stay, but water, grease and oil cannot. Clean grease or oil with KBS Klean and let the surface dry first.

How Cavity Coater Stops Rust Inside a Cavity

Enclosed cavities are where vehicles rot from. Water and road salt collect inside rocker panels and boxed frame rails, and the paint that protects the outside of a panel never reaches the inside face. Cavity Coater treats that inside face three ways:

It penetrates. Cavity Coater wicks into welds and seams by capillary action, reaching metal that primers and topcoats cannot.
It displaces water on contact. Moisture on the metal is pushed out instead of sealed in underneath.
The film self-heals. The cured film closes back over itself after minor abrasion, so protection holds without reapplication.

Do You Have to Remove the Rust First?

No. Cavity Coater needs minimal preparation: remove the loose, scaly rust that is readily accessible and leave the rest. That is what makes it practical on an assembled vehicle you are not tearing down.

Getting It Into the Cavity

For most jobs, attach the Cavity Wand to the Cavity Coater Aerosol, feed it through a 1/4 inch hole, and spray as you pull it out at about 2 inches per second. For bulk quart and gallon work, see spraying Cavity Coater with a Schutz gun. The Cavity Coater directions have the full process.

Protect Both Sides of the Metal

Pair Cavity Coater on the inside with RustSeal on the outside. Apply RustSeal first and let it cure, then do the Cavity Coater. The order matters because getting Cavity Coater on exterior surfaces during application is normal, and RustSeal will not adhere to Cavity Coater. Cavity Coater on fully cured RustSeal causes no problem.

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Frequently Asked Questions: Cavity Coater and Existing Rust