Rust blueing, also known as browning or rust bluing, is a chemical process that creates a protective and aesthetically pleasing dark blue-black patina on steel and iron. This finish isn't just for looks; it offers corrosion resistance superior to plain metal. While seemingly simple, achieving a successful rust blue finish requires precision and patience. This guide will walk you through the process step-by-step, ensuring you achieve professional-looking results.
Preparing Your Metal for Rust Bluing
Before you begin the actual rust blueing process, proper preparation is crucial for a successful and even finish. Neglecting this step often leads to inconsistent results.
1. Cleaning and Degreasing:
Thoroughly clean the metal surface. Any grease, oil, or dirt will prevent the bluing solution from adhering properly. Use a degreaser specifically designed for metal, followed by a thorough rinsing with clean water. Consider using a wire brush or fine grit sandpaper to remove stubborn imperfections or existing finishes. Finish by completely drying the metal with a clean cloth.
2. Polishing (Optional but Recommended):
Polishing the metal to a high sheen is not strictly necessary, but it will result in a more even and attractive final finish. Use progressively finer grades of sandpaper (e.g., 220, 320, 400 grit) and then a polishing compound to achieve a smooth, uniform surface. Remove all polishing compound residue completely before proceeding.
The Rust Bluing Process: A Step-by-Step Guide
This process involves repeatedly applying a rust-inducing solution and then neutralizing the rust to form the blue-black patina. There are several variations, but the core principle remains the same.
1. Preparing the Bluing Solution:
Several methods exist for creating a rust bluing solution. One common approach involves using a solution of ferric chloride, which can be purchased from various metalworking supply stores. Always follow the manufacturer's instructions carefully as the concentration will vary depending on the specific product. Safety precautions, including proper ventilation and the use of protective gloves and eyewear, are absolutely essential when handling ferric chloride.
2. Applying the Bluing Solution:
Apply the solution to the prepared metal surface using a cotton swab, brush, or immersion, depending on the size and shape of the piece. Ensure complete coverage. Allow the solution to react with the metal until a light rust begins to form. This timing can vary; closely monitor the progress. It's often advisable to start with shorter times and increase as needed.
3. Neutralizing the Rust:
Once a light rust has formed, carefully neutralize the rust using a neutralizing solution (often a weak alkali solution, such as baking soda in water). Scrub the metal gently to remove the loose rust. Rinse thoroughly with clean water.
4. Repeating the Process:
Repeat steps 2 and 3 multiple times, allowing the metal to rust lightly with each application. Each application will deepen the color and build up the protective layer. The number of repetitions depends on the desired depth of color and the type of metal.
5. Final Cleaning and Oil Treatment:
After achieving the desired color, thoroughly clean and dry the metal. Apply a thin layer of oil (such as gun oil or a light machine oil) to protect the finish and prevent further oxidation. This final oiling is crucial for maintaining the blueing's longevity.
Maintaining Your Rust Blue Finish
To preserve the beauty and corrosion resistance of your rust blue finish, regular oiling is essential. Periodically apply a light coat of oil and buff it gently to maintain the luster and protective layer.
Safety Precautions
Remember: Always work in a well-ventilated area, wear appropriate safety gear (gloves, eye protection), and follow the manufacturer's instructions for any chemicals used in the rust bluing process. Ferric chloride is corrosive, so handle with care.
This comprehensive guide provides a solid foundation for successfully rust blueing your metal. Remember, patience and attention to detail are key to achieving a beautiful and lasting finish. Experimentation is part of the process, so don't be afraid to try different techniques and times to perfect your results.
