Slow rust bluing got its name because it's slow, but the process is really
pretty simple. Let me show you how it's done.
Rust bluing provides a very durable satin finish. It's a traditional way to
blue fine firearms, such as the barrels on this British side-by-side by William
Cashmore and this Griffin and Howe sporting rifle. I previously polished all
the parts to 320 grit. To begin I'll need just a few basic items: gloves, acetone,
hangers, rust bluing solution, and some cotton pads. I'll install some wooden
plugs in the barrel. This will prevent any of the solution from entering the
bore and give me a handle to hold on to.
Acetone is used to thoroughly degrease all of the parts. Absolutely all traces
of oil and grease must be removed or the parts will not blue properly. I'm using
Pilkington's rust bluing solution. It's best to pour the solution into a
separate container so the entire bottle doesn't get contaminated. It must be
applied very sparingly, be sure to squeeze the pad almost dry any runs will
show up as streaks. Use long strokes, the full length of each part, do not rub. I'm
looking for a nice even coat that just barely wets the surface and dries
quickly. After going over each part I'll hang it in a damp box for one hour. The
box is necessary if there isn't enough humidity in the air to allow the parts
to naturally rust the damp box allows for control of the temperature and
humidity and helps the parch rust evenly. It uses a light bulb and a pan of water
to add additional heat and moisture to the air. Once the parts have rusted for
an hour each one is given another coat being sure to get any spots missed the
first time then back into the damp box. The parts stay in the damp box until
they develop a nice coat of red rust. Be careful, if you let them rush too long
they will develop deep pits and ruin the finish. I then place them in a tank of
boiling distilled water for 20 minutes this turns the red rust to black.
After removing the parts from the water they are covered with a fine black
velvet this is simply the loose rust and needs to be carted off after the parts
have cooled to room temperature. I do the larger parts with a fine
carding wheel, it's six inches in diameter with three thousandths stainless
steel bristles and turning it about 800 RPMs. The smaller parts will have to be
done with #04 steel wool. I've also degreased it with acetone. As you can see
some parts turn darker faster than others and these don't seem to have
rusted much at all. The damp box does help tremendously in getting a nice even
coat of rust. I'll knock the plugs out of the barrel after each boiling and run a
dry patch through the boar to make sure I don't have any rust where it's not
wanted. This process of applying, rusting, boiling, and carding is repeated as many
times as necessary until a dark even black color is achieved on all of the
parts. These parts took seven applications to get a nice even finish.
The final step is a coat of boiled linseed oil to stop the rusting process.
This is traditional but any good gun oil will work fine. I'll give everything a
generous coat then wipe off the excess
and let it cure for 24 hours. Then give all the parts a coat of gun oil. I'll be
sure to dispose of these oil soaked towels properly so they don't spontaneously combust.