Ospho Rust Converter and Metal Treatment 3.79 L - Converts Rust & Primes for Paint

Ospho Metal Treatment Gallon is a professional-strength rust converter that chemically transforms surface rust and primes metal for repainting on cars, boats, trucks and other equipment.

Designed for automotive, marine and industrial use, this one-gallon formula from Ospho penetrates flaky rust, stops further corrosion at the surface, and creates a stable base for primers and topcoats. It works on ferrous metals and is formulated to be compatible with common vehicle paints, decals and non-metal components when applied according to directions.

How does Ospho stop rust and prepare metal for paint?

Ospho contains active ingredients that react with iron oxides, converting loose rust into a dark, adherent layer that bonds to the metal and resists further oxidation. That conversion provides a consistent, paintable surface without the need to remove every trace of old rust. After conversion and drying, the treated area accepts primer and topcoat much like a clean bare metal surface.

• Chemically converts iron oxide into a stable, paintable surface
• Reduces the need for extensive mechanical rust removal
• Creates a uniform substrate for primers and paints

Is Ospho safe to use on vehicles, boats and surrounding components?

When used as directed, Ospho is compatible with most vehicle paints, decals, wiring and hoses; avoid prolonged exposure to non-metal parts and sensitive finishes. Work in a ventilated area, mask adjacent finishes and rinse or protect rubber, plastics and chrome before application to prevent unintended contact.

• Formulated for automotive and marine exterior use
• Protect non-metal parts and delicate finishes from overspray
• Indoor use possible with adequate ventilation and protective equipment

What are the practical steps to use a gallon of Ospho on a project?

Start by scraping loose rust and cleaning the surface of grease and dirt; then apply Ospho with a brush, roller or sprayer, allowing it to react until the rust darkens and stabilizes. Rinse or neutralize per product instructions if required, let it dry fully, and follow with primer and topcoat for best corrosion protection and appearance.

• Remove heavy flakes, oil and dirt before treatment
• Apply evenly and allow chemical reaction time (observe color change)
• Finish with primer then paint once dry for long-term protection

How much coverage will one gallon provide and how long does it last?

Coverage depends on surface texture and application method; expect roughly 200–400 square feet per gallon on moderately corroded, smooth metal when applied thinly. Store the sealed gallon in a cool, dry place away from heat and freeze; shelf life varies, so check the label for recommended storage duration.

• Typical coverage: ~200–400 sq ft per gallon on smooth surfaces
• Heavily pitted or porous metal requires more material
• Store sealed and upright, protected from freezing and direct sun

Who this is for: Ospho Metal Treatment Gallon is aimed at mechanics, body shops, boat owners, fleet managers and DIY enthusiasts who need a reliable rust-treatment solution that both halts active surface corrosion and produces a sound base for repainting. If you maintain vehicles, trailers, marine hardware or outdoor equipment and want to extend metal life while simplifying surface prep, this concentrated gallon is a practical choice.