The KBS 3 Step System: How to Prep Rusty Metal for Paint

KBS Coatings products are designed to work as a complete system. RustSeal will provide superior rust protection even over a minimally prepared surface, but only the KBS 3 Step Oxygen Block System gives you the surface preparation and the rust stopping power together.

It does not matter how good a rust prevention product is if the surface is not prepared properly. Corrosion and organic contamination block a coating from penetrating and permanently adhering, and even new metal carries protective surface oils that interfere with adhesion. The cleaner the surface after KBS Klean, the more effectively RustBlast works, and the deeper RustSeal penetrates into the pores to seal and protect.

Freshly sandblasted metal is the exception. Newly blasted metal (fresh sand, not recycled) that has been handled with gloved hands is ideal for a direct RustSeal application, and needs nothing more than blowing off loose dust before Step 3. Plastic media, bead, and soda blasted surfaces do not leave enough abrasion, so they still need the RustBlast etch in Step 2.

Starting point: untreated surface rust.

Start by removing loose, flaking rust by sanding with 320 grit sandpaper, wire brushing, or wire wheeling until you have a solid surface profile. Then remove all surface contamination. Slight residues of grease, oil, or fingerprints can ruin an otherwise good paint job.

KBS Klean is a concentrated water-based cleaner and degreaser and should always be diluted with water. The warmer the water, the more effective the cleaning action. For general purpose cleaning, apply the solution liberally and wash the surface for 5 to 10 minutes. For heavy-duty cleaning, extended soaking of 24 hours or more may be necessary. Use a bristle brush or scouring pad on heavily soiled surfaces and retreat as needed until clean. KBS Klean may also be used in power washing equipment.

Do not allow KBS Klean to dry before rinsing. Rinse thoroughly with water and let the surface dry. Avoid solvent-based cleaners at this stage: they leave an invisible residue that interferes with adhesion and appearance. Metal cleaned with KBS Klean should always be treated with RustBlast before painting.

After Step 1: clean, oil-free metal.

Apply RustBlast full strength to a clean, dry surface using a spray bottle, brush, roller, or backpack sprayer for larger areas. Never dilute it. Shake well before each use. RustBlast works more effectively when the surface and the ambient temperature are warmer, and the ideal working range is 55 to 90 degrees F.

Re-apply often and as needed so the surface stays wet for a minimum of 30 minutes on smooth or lightly rusted surfaces, 40 to 60 minutes on moderately rusted surfaces, and 1 to 2 hours on heavily rusted or corroded surfaces. Do not allow the surface to dry during this time. For light corrosion or etching on non-ferrous metals such as aluminum, brass, and copper, apply RustBlast for 10 to 20 minutes only.

Rinse thoroughly with water before the RustBlast dries, then allow the surface to dry completely. Rinsing late leaves a heavy zinc phosphate layer. Once dry, the slight white powder residue you see is zinc phosphate, and it aids the adhesion of RustSeal and most other coatings. Items should typically be coated within 7 days of treatment.

To remove rust from tools and hardware, soak the item in RustBlast for 30 minutes up to 24 hours, then rinse with water using a Scotch-Brite pad.

After Step 2: etched, rust-free, ready to seal.

Apply RustSeal to prepared surfaces by brush, roller, or spray equipment. Brush marks level out as if sprayed, so brush an area once and move on rather than working it repeatedly.

The ideal application temperature range is 55 to 82 degrees F (13 to 28 degrees C), with 30 to 80% relative humidity. RustSeal is moisture-cured, so it draws what it needs from the air: higher humidity shortens cure time and lower humidity lengthens it. Do not apply it in rain or in humid conditions where the surface cannot be kept dry, since damp surfaces can bubble and adhere poorly.

Stir RustSeal thoroughly for several minutes, repeatedly touching the bottom of the can and lifting to disperse settled pigment. Do not paint directly out of the can. Pour a working amount into a separate steel or glass container and reseal the original can right away.

Always apply a minimum of 2 thin covering coats at 2 mils each for general applications. For marine or industrial applications, apply a minimum of 3 coats. Recoat once the previous coat is dry to the touch and leaves no fingerprint, typically 2 to 6 hours depending on temperature and humidity. If more than 8 hours pass before recoating, wait a full 24 hours and lightly scuff the cured coat with a 320 grit green Scotch-Brite pad first.

Never apply RustSeal in thick or heavy coats, and never apply the next coat before the previous one is dry to the touch. Both cause the top layer to skin over and trap solvent gas underneath, which shows up as surface bubbling. Thinning is not generally required, but if needed, 5 to 10% with KBS #1 Thinner or Xylene is normally adequate. Never reduce RustSeal with lacquer thinner.

After Step 3: a hard, non-porous RustSeal shell.