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Bern Rust Bluing Procedure

Please note that if you are using this formula, Spirit of Nitre is open to conjecture as to what it is. My chemist merely added ethyl alcohol instead. Spirit of Nitre is USUALLY Nitric acid, but can also be fuming nitric acid. If it is Sweet Spirit of Nitre, it is ethyl nitrite, which is an explosive liquid that MUST be stored under alcohol. OK, disclaimer over!

So, to rust blue:
1. Fully prep the metal. If you are applying it over a worn area, simply degrease the area. If a full re-blue, it is best to remove the old blue with naval jelly (can use phosphoric acid, but diluted, as regular phosphoric acid will essentially parkerise the area!) or hydrochloric acid. I prefer hydrochloric acid. This is referred to as pickling. it also slightly etches the metal, which is good.

If you wish to polish the metal, I would go as high as 300 grit to polish.

2. Degrease again. I prefer to degrease is caustic soda solution, but alcohol or thinners will work if you must. never tried any of those orange goo's, so no idea there.

3. LIGHTLY shake the bottle you have the solution in to mix any displaced chemicals. Ball some 100% cotton wool into a tight mop, and hold it with a clothes peg (the spring clip type), or a haemostat (Kelly clamp) - stainless stell of course!!!!!

4. Apply the cotton mop to the surface of the metal just enough to coat the metal without any puddles or runs. Go easy. Finish the entire area, slightly overlapping each line. NEVER, repeat, NEVER go over any solution you have laid dow - you will merely remove it!

5. Leave the solution to work on the metal for about 4 hours. It will evaporate and start to rust (or at least an orange oxide layer will form). LIGHTLY reapply some solution to kick start it again.

6. leave it at least over night - I usually leave it 2 whole days to rust well! DON'T TOUCH THE RUSTED AREA!!!!

7. Get a stainless steel stock pot, or if you can, a trough long enough (if doing an entire rifle) I simply use a 20 litre stock pot. Fill with water (demineralised is preferred, but I sually use tap water), and bring to the boil. Put the rusted area or part into the boiling water, and boil them for 10 minutes.

8. Remove from the water, and it should instantly dry, revealing a black oxide layer. If you DON'T have a black oxide layer, you screwed up somewhere (ok, an orangey black layer is OK, but is not a full reaction)

9. Grab some 0000 steel wool. Soak it in alcohol to remove the preservative oils. Now, having done that, LIGHTLY scratch off the black oxide with the steel wool. You should see a greyish blue area (in dull light it looks blue, but under strong light, it will be grey). DON'T overdo the steel wool scratching!!!!!

10. Reapply the solution, as before, being LIGHT handed. Let rust for a MINIMUM of 6 hours, and repeat as above as many times until you reach the desired hue. I found 3 applications matched the original blue PERFECTLY.

11. Let the finished area stand overnight. Don't touch it, don't oil it, just bloody leave it alone!

12. Inspect it, and if any after rusting has occured, lightly reboil and scratch as before. If not apply your favourite oil - preferrably one that is merely oil with no other anti-rust additives. Since blue IS rust, applying an anti-rust preparation can hurt it! I do NOT recommend using any moly oils, or any CLP's or Break Free's or wahtever - simple "3 in 1" (or Singer Macine Oil) works PERFECTLY.

That's it. Time consuming, but worth every minute of it!

I will confess - I removed those GHASTLY CAI import marks on the barrel of my K31 (you know those dreadful machine-#####ed type!). Thankfully, the #####s are VERY lightly struck, so I easily removed them with some emery paper. I then matched the original texture to the "corrected area", and reblued it. 3 applications, and under even VERY strong light I cannot see a demarcation or colour difference!

Before anyone throws legal crap about removing import marks, remember I am in Australia, and import marks are NOT required - since the rifle was imported from the USA from CAI, I couldn't escape it.

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