Gun barrels, receivers and other hardware found on firearms are all made of metal and as a result they are susceptible to corrosion. Browning, also called russeting, is a chemical process that changes the chemical structure of the metal surface of the gun to reduce corrosion. The process is several hundred years old and has been replaced in modern times by a process that changes the color of gun metal to a deep blue. However, the browning process is still used to replicate classic firearms and to restore antique firearms to their original condition.
Mix the nitric acid, sweet spirit of nitre, blue vitriol and tincture of steel with 32 ounces of distilled water--do it slowly and carefully to prevent splashing. Stir the mixture vigorously with the glass rod for one minute, then set it aside.
Remove all dirt, grease, oil and corrosion from any gun metal that will be treated by using a dilute detergent solution of three drops of detergent to one quart of water. For heavy corrosion, use steel wool to remove scales and oxide. When you're finished cleaning, dry the metal completely.
Apply the browning solution with a sponge to all metal surfaces to be treated. When all metal surfaces have been wiped gently with the browning solution, heat the metal using an alcohol lamp. When the metal is warm to the touch, use a hard bristle brush to move the newly formed brown oxide around the metal. This will help produce a uniform application of the oxide coating.
Repeat the wiping, warming and brushing process until the desired patina has developed, then rinse the browning solution from the metal by wiping with a clean sponge and 2 quarts of boiling water in which 10 grams of potash has been added (This measurement does not need to be exact). Wipe the metal gun parts several times, until the water running off of the gun metal is clear.
Dry the metal that has received the browning treatment immediately and completely, then rub it smooth with a hard wood burnisher. After burnishing, lightly oil the metal with gun oil.
- Use eye protections and chemical resistant gloves when working the the browning solution.
- Do not allow nitric acid to come into contact with skin or eyes because it is highly corrosive.
- Use only an alcohol lamp for warming the barrel because it produces a low temperature flame.
- Work on small areas when possible. Do not attempt to brown the receiver, barrel and all hardware at the same time.
- Repeat the process to get the desired brown patina.
- The metal can be coated with a varnish coating if you wish, but this is not part of the browning process.
- "Firearms Blueing and Browning, Revised Edition," R.H. Angier; 1936
- "Professional Gunsmithing: A Textbook On The Repair and Alteration of Firearms," Walter J. Howe; 2008
- "Gunsmithing," Roy E. Dunlap; 1963
- Pistole image by Volker Schwere from Fotolia.com