MARK LEE METAL FINISHING FORMULAs
FINISHING TWIST BARRELS USING SLOW RUST #3
The object is to make the pattern of the twist barrels show a vivid contrast. Rust bluing or browning will be one solid color unless special procedures are followed. This method works by stripping or loosening the color produced by bluing or browning using an etchant. (Ferric Chloride Solution) The rust is removed or loosened easier on the harder steel used in the twist pattern.
What you will need:
Remove pitting with files and or abrasive paper. Your metal preparation will probably begin with a coarse grit abrasive paper, but should be completed by using 320 or 400 grit.
What you will need:
Degreasing is essential in getting fine results. Parts should be soaked in hot soapy water using a cleaner such as Simple Green. Scrub parts with a brush during the cleaning process. Remove parts from the cleaning solution with tongs or hooks. Rinse thoroughly with hot water, and dry with compressed air or blot with paper towels. Do not touch cleaned parts with bare hands as the oils from your body can contaminate the metal. Wear cotton gloves while handling degreased metal parts.
What you will need:
Apply a coat of Slow Rust #3 diluted 2 parts of distilled water to 1 part Slow Rust #3. Apply as evenly as possible using a sponge cut into a 1 inch square. Place barrel in a humidity box at 90 deg. F. and 60% humidity until covered with a coat of rust. Different temperatures and humidity will work but the rusting times will vary. (1/2 hour – 5 hours)
Remove barrel from the humidity box and dip in the Ferric Chloride etchant for 5 seconds. Dip in room temperature water and rub with oil free steel wool under water. Dry the barrel and apply a coat of Slow Rust #3 diluted 4 parts water to 1 part Slow Rust #3. The application should always be done at room temperature. Place barrel in the humidity box and wait for a coating of rust to form. Remove from humidity box and place in Ferric Chloride etchant for 5 seconds. Rinse in clean water and rub with steel wool. Dry the barrel and apply another coat of Slow Rust #3. (4 water to 1 Slow Rust) Place in the humidity box, rust, etch (5 seconds), dip in water, and rub with steel wool. Apply Slow Rust #3 diluted to 6 parts water to 1 part Slow Rust #3. Place in the humidity box until a coating of rust forms, etch (5 seconds), dip in water, and rub with steel wool. The pattern of the twist barrel should be getting more vivid. Repeat the sequence using the Slow Rust #3 diluted to 6 parts water and 1 part until satisfied. It will probably take about 8 sequences. After you are satisfied with the pattern soak for 5 minutes in baking soda and water to neutralize any acid residue. If a darker plum brown is desired, barrel can be boiled in water and removed when the desired darkness is achieved. If a black and white pattern is desired boil in water after every rusting operation. Rinse in clean water, dry, and apply Rig gun grease and set aside for 24 hours to cure. Some finishers also apply a coating of wax or lacquer to the finished barrels.
The Radio Shack Ferric Chloride Solution is 35%. Dilute this solution 8 parts of distilled water to 1 part Radio Shack Ferric Chloride Solution. If this solution removes the color too easily it can be diluted further.
Rubber stoppers are needed to keep the etchant from getting inside the barrels. Chemical stoppers with a hole work well for double barrels. Thread the ends of a brass rod that is the correct size for the stoppers and attach using washers and nuts. These will not blow out in boiling water. The rods also make good handles. Check for leaks in clean water before starting procedure. Bores can also be oiled before installing plugs.
During the whole bluing or browning operation don’t touch the metal with your bare hands as you can leave contamination spots in the finish.
If you use steel wool for carding make sure to buy oil free steel wool. It is available at fine wood working stores. Start off using the finest grade available but have medium on hand as you might prefer it.
When placing parts in a humidity box let the metal come up to the temperature of the box before adding humidity so that water droplets don’t form on the parts. If that does happen take parts out, boil, card, and recoat.
Temperature and humidity can be varied so the rusting time can vary greatly. I usually run mine at 90 deg. F with 60% humidity. Winchester was running their humidity box up to 150 deg. F with 95% humidity with rusting cycles from 7 to 15 minutes. Parts have to be watched.
A humidity box can be made of plywood. Heat the box with a heat lamp. Humidity can be added by hanging a wet cloth in the box. The box should have a very small fan to keep the air moving which keeps the temperature and humidity consistent throughout the box. A temperature and humidity gauge can be mounted to the box. A window is very helpful so you can see the rust forming. When the parts are covered with brown rust they are ready to be boiled in order to convert the rust to black oxide or Fe3O4. Remember to let parts heat up to temperature before adding the humidity.
If you don’t have a boiling tank and are only going to do a few guns you can buy a piece of PVC pipe, glue a cap on one end, hang your barrel in the pipe and fill the pipe with boiling water each cycle. The PVC pipe will also work well for the Ferric Chloride etchant. A plastic wall papering tray can also be used.
After initial cleaning, a light scrub down with a 3M Scotchbrite pad while in the water rinse is often helpful to insure that all cleaner residue is removed.