EXPLORE OUR INFO CENTER
     
|
Introduction To Patinas.
On Brass, Bronze and Copper
A patina is a film formed on copper, bronze or other metal by natural weathering or by artificial treatment with chemicals. The advantage of a chemical patina is that it can be produced in a short time and, with practice, with a predictable appearance. In order to achieve consistent results, however, metal artisans have developed certain methods and approaches to meet this end.
Below are discussed basic equipment and procedures that can help lead to a successful patina project.
Basic Equipment used for Patina work -
- Chemicals (click to see list), depending on formulas employed.
- Water. Distilled water gives most consistent results.
- Containers for mixing and storage.
- Scale for measurements by weight. Graduated cylinders or beakers for volume measurements. Spoons and scoops for other dry measures.
- Heat source such as a roofer's torch, propane torch or heat gun. Temperatures usually to exceed 100°C (212°F).
- Spray bottles and brushes for applying solutions.
- Safety equipment to protect hands, eyes and lungs. Good ventilation.
- Heat proof stand to place heated work on.
- Cleaning and rubbing supplies such as detergent, solvents, Scotchbrite pads or steel wool, Bon Ami scouring powder, paper and cotton towels.
- Wax, Johnson's Paste wax or Moser's paste wax (from Woodworker's Supply).
Metal Preparation
Clean the metal surface - All traces of oils and oxidation should be removed before applying patina chemicals. The most common oils are oils from your hands. Use rubber gloves during washing and subsequent handling. Surfaces can be cleaned by bead-blasting immediately before patina application. A soaking in 10% sulfuric acid for 5 to 6 hours also serves to remove any traces of surface dirt or oil. Other methods include a good detergent wash and rinse in water followed by wiping with a solvent like methyl alcohol. Rubbing with Scotchbrite pads or steel wool during washing improves the surface for patina by removing oxidation. Dry with compressed air, clean towels or a hair dryer. Patina within 1/2 hour.
Variables affecting patina results:
- Composition of the metal.
- Patina formula used.
- Purity of chemicals and water used.
- Surface preparation including oil and oxidation removal and thoroughness of washing.
- Method of application:
- Hot Process (hot solution, hot metal, hot rinse water).
- Cold Process (cold solution, cold metal, cold rinse water)
Maintenance of finished patina.
Once a patina has been created on a metal surface it can be left to continue weathering naturally. Weathering can be arrested at the desired point by applying a suitable oil, e.g. raw linseed oil or lemon oil. Colored finishes can be protected with a nonporous lacquer or a wax coating to improve their resistance to scratching, flaking and tarnishing. Apply wax while the work is still warm to seal the patina. Re-wax when completely cool and buff.
|
