Blued (oil blackened) versus Parkerized

[Sapper740]

I've in recent years experimented with concentrated HNO3 & it works well, so long as you do not expose the piece for too long, as the acid will soon etch into the surface & cause pitting. You definitely need your sensible head on, though, when using such unpleasant chemicals......good gloves, face mask, eye protection, good ventilation etc.

When you say concentrated Nitric acid is it fuming when exposed to air? That would be the most concentrated form at about 21M. We experimented with fuming Nitric acid in our chem labs in college and it is very nasty stuff, only used in fume hoods and kept well away from water as it would boil, splashing nitric acid everywhere if water is added to nitric acid instead of the other way around.

[browningautorifle]

only used in fume hoods and kept well away from water as it would boil, splashing nitric acid everywhere if water is added to nitric acid instead of the other way around.

Yes you want a large evacuation hood running if bluing in a closed shop. We added the salts to water without incident as it's salt crystals and Parkerizing is a blueish liquid. No incidents.

I'm going to pour myself a half gill of bourbon.

You're in Texas now? Make it a half gallon...

[Roger Payne]

Without going out to check the container I think it is 58%, which is concentrated but just short of fuming. I use it outside, very carefully.

[Sapper740]

Yes you want a large evacuation hood running if bluing in a closed shop. We added the salts to water without incident as it's salt crystals and Parkerizing is a blueish liquid. No incidents.



You're in Texas now? Make it a half gallon...

We used to call the half gallon bottles of spirits that we bought in Washington state a "Texas Mickey". Do they still sell Mickeys in B.C. and is a 26er still 25 ounces?

[browningautorifle]

We used to call the half gallon bottles of spirits that we bought in Washington state a "Texas Mickey". Do they still sell Mickeys in B.C. and is a 26er still 25 ounces?

The Texas mickey is the big tall bottle, I don't see them now. I still have one a recruit section gave me in '82, empty now formerly 133.3 oz. The 26 oz bottle reduced in content when it became 750 milliliters it's now about 25.36 fluid ounces. I haven't drank since '07 so I don't hear anyone call it anything now. Don't know what they cost either, must be frightening.

[Peter Laidler]

We used to pil blacken lots of small parts - until health and safety started to bite. Then it was bead blast, phosphate and paint which was as good as it gets.

Ah, yes..... health and safety. But it didn't seem to affect the main workshops where there was a boiling vapour tricholethylene tank deep enough and wide enough to take a Bedford lorry chassis and a Centurion gearbox. Plus my MGB GT V8 cross member, axles, Norton Commando frame and..... and.....

[Bruce_in_Oz]

"Oil blackening is applied with heating a metal pert and quenching in oil to cause black finish...which isn't so durable."

A variation on Oil Blacking is "Blazing Off.

This is generally used on low-Carbon items (malleable cast iron, as specified in the original documents.

The part (often screws and washers, is heated then "quenched quickly in a "suitable oil", the still HOT item ignites the oil immediately after that "quick quench and it burns off, leaving a thin "black" oxide surface. This, just like Parkerizing, blueing / browning, has a porous structure which conveniently holds a "film" of oil which reduces the rate of "corrosion. A Zillion small arms components, from early Ordnance muskets to the Bren (and possibly later?) had "low-stressed" screws and other components components thusly finished by "blazing off". It seemed to work OK.

Phosphating / "Parkerizing requires a "grit-blasted" surface for best application. "Grit-blasting" springs is a guaranteed way to induce "stress-risers" in the spring steel and thus premature cracking / catastrophic failure

[Surpmil]

I have a 1913 Mk.III that was refurbished at RSAF(E) in 1931. The cocking piece, trigger, safety and spring and cutoff are all oil-blacked in contrast to the fine rust-blue on the body, bolt etc. My recollection was that the blacked parts were dipped in a sort of lacquer or shellac to preserve their finish somewhat. In original condition they show a certain sheen which I don't believe a plain oil blacked surface would exhibit unless highly polished.

Modern hot-tank bluing does not add any sort of layer to the surface, unlike rust bluing or parkerizing. Parkerizing is a "friable" coating which wears away as required and is or was much used in engine rebuilding to hold oil during the first moments of running in.

[Alan de Enfield]

Extract from :

Specification No S.A./462 P, being for Rifle's No1 Mklll, with bantam long, normal and short butt (S.M.L.E., .303-in. With cut-off.)





And it says:

Body -- Steel. B.S.S.5005/401 -- Partially oil hardened, tempered and browned.

Barrel -- Steel. D.D.8 -- (Heat treated)

Bolt, Breech -- Steel. D.D.8 -- Oil-hardened, tempered, polished and browned or oil-blacked.

Head, breech bolt -- Steel B.S.S.5005/103 -- Case hardened and polished

[Surpmil]

There is a peculiar dull "ring" to No.1 bolts as opposed to the No.4. Bodies the same AFAIK.