What you will need:

  • abrasive paper (preferably cloth backed) 120-400 grit

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:

  • detergent (Simple Green)
  • scrub brush
  • tongs or wire hooks
  • air compressor or paper towels
  • clean cotton gloves

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.

ETCHING (Optional)

What you will need:

  • sandblasting gun
  • 150 grit garnet (aluminum oxide can be used)

Etching helps the first applications to take hold of the base metal. Etching can be accomplished chemically (acid dip) or mechanically (blasting with media). I do not recommend using acid because it is too hard to control. Blasting with 150 grit garnet is the best. The polished metal will appear dull grey after blasting but the process of rust bluing will bring the sheen back. The finish will look almost the same whether it is blasted or not. The blasting is best to do after the degreasing and parts should only be handled with clean cotton gloves.

Warning:  Do not blast with glass beads as the beads produce different textures to hard and soft steel.


What you will need:

  • vinyl or latex gloves
  • cotton gloves
  • natural sea sponge, cellulose sponge, or cotton swabs
  • small glass or plastic container
  • steel wire brush (.003-.005) or oil-free steel wool
  • container for boiling distilled or deionized water (tap water can be used in many parts of the country but it depends on the mineral content in your area)
  • humidity box

Pour solution into small glass or plastic container. Use vinyl or latex gloves during application. If you are using natural sea sponge or a cellulose sponge cut the sponge into one inch pieces. The object is to get the thinnest most even coat possible. Apply to barrels in long even coats keeping overlaps to a minimum. You will get a feel for how wet to get the sponge. The metal should be at room temperature before applying any slow rust solution. The first application will probably bead up on the metal unless the parts have been etched. Wipe over the coated parts with the sponge without adding any new solution and set aside for 15 minutes. The parts will start to turn green. Apply a second coat. This time the solution should wet out evenly on the steel. If not rub with sponge again.

Now place the parts in your humidity box. (I run mine at 90 deg. F and 60% humidity) When the parts are covered with a brown rust (usually about 2 hours) remove from the humidity box and place in boiling water for 5 minutes. Remove the parts and dry. They will be covered with what looks like black soot. Using cotton gloves wire brush or steel wool to remove the residue. The color will be silver grey or black depending on the type of steel and whether the parts were pre-etched. After the parts have cooled to room temperature apply another coat of bluing solution. Apply just one coat and place back into the humidity box. It will probably take about 5 hours for this coat of rust to form.

Boil in water to convert the brown rust to black rust and card. Repeat this sequence three more times and the parts should be done. Never apply more than one coat of solution between boiling and carding except the first coat. When satisfied with the metal finish, oil parts and coat the bluing with RIG (gun grease) and leave set for 24 hours.


What you will need:

  • baking soda

This step can eliminated if fresh water is used to boil the last few coats. Soak blued parts in a solution baking soda and water at room temperature for 5 minutes, rinse and oil.


During the whole bluing operation don’t touch the metal with your bare hands as you can leave contamination spots in the finish.

After the first boiling and carding examine the metal under the light of a regular light bulb or sunlight. If you see any shade of brown or purple card the metal until the metal is silver, grey, or black. Applying coats over the top of bad color will lock it in. You usually won’t see it happen again after the first boiling and carding.

If you have a very small spot along a rib that doesn’t want to take color, take a piece of new 400 grit paper and scuff the small area. The next coats should take.

If you use steel wool for carding make sure to buy oil free steel wool It is available at fine wood working stores.

Garnet is preferred for etching as it is unlikely to imbed in the metal. This is only a concern on parts that rub against each other such as the bolt.

Do not try to blue the ends of a barrel because you don’t want to get any bluing solution in the bore. Polish the barrel crown back to white after bluing. I don’t plug bores anymore but I make sure I’m using fresh water when doing barrels.

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 F with 60% humidity.   Winchester was running their humidity box up to 150 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.

Parts can be strung on a wire for boiling but don’t wire brush the parts with the wire attached. I almost lost an eye when the wire brush grabbed the string of parts.

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.

Sometimes carding with steel wool and water can blend a streak in the blued finish.

Rust bluing can be lightly buffed with a loose muslin wheel and a compound used for mirror finishing. This adds a little sheen to the finish. This operation can be done just before applying grease or oil to the finished parts.

Slow Rust #3 solution can be diluted up to 50% by adding distilled water. The purpose is to tone down the strength for certain steels or when trying to achieve a finer grain finish. I would only recommend diluting the solution to experienced finishers.