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Prices in USD. Free tracked shipping on 3-bottle bundles and above.
Rusted metal in, paint-ready surface out
Brush RustGuard™ over sound rust, let it cure, then paint. Images are illustrative — results depend on surface condition and preparation.
Where rust shows up first
The areas worth checking before you order.
- Wheel arch lips and inner arches where road salt collects
- Sill and rocker panels below the door seal line
- Floor pans and footwells, especially under old carpet underlay
- Boot floor, spare wheel well and battery tray
- Subframes, suspension turrets and rear beam
- Bonnet and tailgate seams where water sits in the fold
Step-by-step on this job
- 01
Get the car up and lit
Ramps or axle stands on level ground, wheels chocked, and a bright inspection light. You cannot treat what you cannot see.
- 02
Feather the paint edge
Where rust has broken through, sand back until you reach sound paint with no lifting edge. Vacuum the dust out of the seams.
- 03
Degrease hard
Underbody film is oil, wax and road grime. Wash with detergent, rinse, and let it dry fully — trapped water stops the reaction.
- 04
Brush the converter into the pitting
Work along seams and inside lips with a small brush. Two thin coats on pitted areas beats one heavy coat.
- 05
Cure 24 hours, then topcoat
Chassis paint, underbody schutz or acrylic enamel all go over the cured film. Do not shortcut the cure — trapped moisture blisters the topcoat.
What not to do
The cautions that save a re-do.
- Never apply near brake friction surfaces, discs, pads or wheel bearings
- Mask fuel and brake lines, rubber bushes and electrical connectors
- Keep it off glass, trim and good paint — wipe overspill immediately while wet
- If a screwdriver goes through the panel, it needs welding, not converter
Typical quantities
A starting point based on the jobs customers order for most often.
| Job | Bottles |
|---|---|
| Both rear arches | 1 bottle |
| Sills plus both arches | 2 bottles |
| Full underside of a hatchback | 3–5 bottles |
| Floor pans and boot floor | 2 bottles |
| Full 4x4 or van underside | 5–8 bottles |
Work out your exact quantity
Area
100 sq ft
Bottles needed
3
Recommended bundle
×3 — $42
Based on up to 55 sq ft per bottle on smooth steel, adjusted for surface condition. Estimates only — measure generously.
Frequently asked questions
Will this pass a roadworthiness or MOT test?
Surface rust treated and painted is fine. Corrosion in a prescribed structural area, or metal you can perforate, is a failure regardless of what you coat it with.
Can I use it inside the cabin?
Yes, on the floor pan with carpet and underlay removed. Ventilate the car and let it cure fully before refitting trim.
Do I need to remove the wheels?
For arch work, yes — you want proper access to the inner lip, and it keeps product off the brakes.
What about seam sealer?
Convert first, cure, then apply seam sealer over the treated film and topcoat the lot.
Keep reading
- Rust converter for trucks and pickupsStop frame and bed rust on pickups and light trucks. RustGuard™ converts corrosion in place on ladder frames, bed floors and hitches.
- How to remove rust from a carAssess, treat and repaint car rust yourself: surface rust, scale and bubbling paint on arches, sills and floor pans — plus when it needs welding instead.
- Rust converter for iron and steel that leaves a paint-ready surfaceRustGuard™ rust converter reacts with existing rust and leaves a stable, primed surface you can paint. Bundles from $24 with worldwide shipping.
- How to paint over rust properlyPainting straight over rust always fails. Here's the correct sequence — prep, convert, cure, prime, topcoat — and the paints that work over a converted surface.
- Rust converter for motorcyclesTreat rust on motorcycle frames, swingarms, brackets and fasteners. What to convert, what to strip, and what to leave to a specialist.
Stock up & save
Choose your RustGuard™ bundle
Ships from our US fulfilment partner, typically 3–7 business days. 30-day money-back guarantee.