How to Prepare Metal for Painting: A Guide to Using KBS Klean and RustBlast for Superior Adhesion

Properly preparing metal surfaces for painting is essential for achieving a durable, professional-looking finish. Without the correct preparation, paint can fail to adhere to metal, leading to peeling, rust, or uneven coverage. In this article, we will explore the steps to prepare metal for painting, with a focus on two highly effective products: KBS Klean and RustBlast. We’ll also discuss factors that can limit adhesion and ways to overcome these challenges.

The Importance of Proper Surface Preparation

Before applying any paint to metal, it’s crucial to clean and prepare the surface thoroughly. Metal surfaces often have grease, oil, rust, dirt, and other contaminants that can interfere with the adhesion of the paint. Even a thin layer of residue can cause the paint to peel off prematurely.

Properly prepping metal for painting not only enhances adhesion but also ensures that the paint will be able to protect the metal from corrosion, wear, and environmental factors. By following the right steps, you can achieve a surface that’s conducive to a beautiful and long-lasting final finish, whether on outdoor equipment, automotive parts, or home decor.

Step-by-Step Process to Prepare Metal for Painting Using KBS Klean and RustBlast

1. Remove Loose, Flakey Rust: The best way to prep rusty metal for paint is to remove any loose or flakey rust as a first step. Doing this provides a stable surface to receive paints and coatings. This can be done with 320 grit sandpaper, a wire brush, or by sandblasting.
2. Clean the Surface: The next step in preparing metal for painting is to clean the surface. This step is vital because even a thin layer of dirt, grease, or oil can prevent paint from bonding properly to the metal. Properly cleaning metal for painting can be done with cleaning products like KBS Klean, which will be effective in thoroughly removing contaminants without leaving a harmful residue, like solvents based cleaner do, that could interfere with paint adhesion.

KBS Klean powerfully removes dirt, grease, and grime effectively from metal surfaces. It works by breaking down oils and other contaminants, allowing paint to adhere strongly. To use KBS Klean, simply mix with warm water, and scrub the metal surface with a sponge, scrub pad, or scrub brush. Afterward, rinse the surface thoroughly with water to remove any leftover cleaner, and dry thoroughly with a clean and lint free cloth or compressed air.

Detailed instructions for use of KBS Klean can be found HERE.

1. Rust Removal and Neutralization: Rust is one of the most common issues when preparing metal for painting. It can prevent paint from adhering properly and may also continue to spread under the painted surface, causing the paint to peel off over time. The best way to handle any remaining rust is to remove and neutralize it before moving on to painting. For this, RustBlast is offered.

RustBlast is a powerful rust remover designed specifically for metal surfaces. It works by chemically dissolving and neutralizing rust. RustBlast is applied directly to the rusted area, where it breaks down the rust. Simply spray RustBlast onto the rusty areas and keep wet/reapply as needed for a minimum of 30 minutes for smooth or lightly rusted surfaces, 40-60 minutes for moderately rusted surfaces and 1-2 hours for heavily rusted or corroded surfaces. All the while intermittently scrubbing the surface with a scrub pad or scrub brush. The intermittent scrubbing sloughs off rust particles as they become loosened by RustBlast. Note, the ideal working temperature for RustBlast is 55-90°F and the surface must always be kept wet with RustBlast and not allowed to dry. Once the rust is removed rinse thoroughly with water and allow the surface to dry completely. Items treated with RustBlast should typically be coated within 7 days. It is recommended to reapply RustBlast if more than 7 days have passed. Please note, a whitish colored powdery residue will be left on the metal after drying. This is a zinc phosphate coating that is to be left in place and not wiped off. Information regarding the coating follows in the “Surface Profile” section below.

Detailed instructions for using RustBlast can be found HERE.

After RustBlast treatment the metal is ready for coating.

Surface Profile: To properly prepare metal for painting, the surface should be roughed up for the strongest adhesion of paints and coatings. This roughness profile, often referred to as an anchor pattern, allows coatings to latch onto the texture peaks and valleys. Traditionally, this is done by sanding or sandblasting, however, RustBlast performs this function by chemically etching the surface thereby avoiding the need for mechanical abrasion. Additionally, RustBlast leaves behind a zinc phosphate powder that enhances paint adhesion. Again, paints and coatings should typically be applied within 7 days. If more than 7 days, reapplication of RustBlast is recommended.

Other Factors That Limit Paint Adhesion on Metal

Before applying paints or coatings to treated metal, it is important to consider other things that can possibly hinder adhesion.

1. Presence of Oils and Grease: Oils and grease are among the most common contaminants that prevent paint from bonding to metal. Handling bare metal without the use of gloves can leave skin oil that can cause the paint to peel, bubble, or fail to adhere.
2. Moisture and Humidity: Moisture on the surface can limit paint adhesion, especially in the form of condensation. If metal is exposed to moisture before painting, the paint may not adhere properly, and rust may form beneath the paint. It’s essential to ensure that the metal is dry before painting. Avoid painting in a high-humidity environment or if the surface temperature is within 5F of the dew point.
3. Contaminants in the Air: Dust, dirt, and airborne contaminants can settle on freshly cleaned surfaces and prevent the paint from sticking. It’s good practice to clean the area where you’re painting to remove airborne debris, and to apply paint in a well-ventilated space to minimize exposure to dust and contaminants.
4. Temperature and Surface Condition: Metal surfaces that are too hot or too cold can affect paint adhesion. Painting in extremely hot or cold conditions can cause the paint to dry too quickly or unevenly, leading to poor adhesion and finish quality. The ideal temperature for painting metal surfaces is typically between 50F and 85F.

Coating Metal Treated with RustBlast

Metal treated with RustBlast can be directly coated with a variety of paints, coatings and primers. This includes treated metal that has light residual surface rust. KBS Coatings offerings include RustSeal, BlackTop, KBS MAXX, KBS Top Coater, KBS Top Coater Aerosol, Motor Coater, KBS Fusion SEP, and KBS Fusion FPP.

• Apply paint or coating within 7 days of RustBlast treatment (etching) when the surface is kept covered, clean, and out of the elements. It is recommended to reapply RustBlast if more than 7 days have passed.
• It is OK to coat RustBlast treated metal if there is remaining light surface rust. As with painting any metal surface, ensure the paint is applied per directions to provide a coating thickness that will not allow moisture and oxygen to reach the metal surface and progress rust. Keep in mind that while RustBlast works effectively to remove rust to provide a stable surface, areas of heavy corrosion may require additional work, such as sanding or scraping.
• Ultimate rust protection is achieved with use of RustSeal rust preventive coating, which can be top coated with any opaque paint system including BlackTop, KBS MAXX, KBS Top Coater, and KBS Top Coater Aerosol.

Questions?

If you have any questions, please let us know. +Contact KBS Coatings.