cleaning tarnished color case hardening

[roundgun]

I inherited a real neat Stevens 22lr rolling block model 18 1/2. It has color case hardening on the receiver but it has tarnished over the years. Has anyone safely cleaned tarnished color case hardening to bring back some of the color? I read an article where a gent used 0000 steel wool some lubricant a real copper penny and a very light touch.

[Chev. William]

Color Case is a Surface Oxide layer for the Colors and deeper Carbon infusion for improved material strength.

The thickness of the oxide layer selectively reflects certain light colors so is Very thin. removing "tarnish" is typically an abrasive process which might also remove the oxide layer; BE CAREFUL and I suggest trying your technique on a small area that would be hidden when the firearm is assembled.

Best Regards,
Chev. William

[waksupi]

Leave the tarnish, or loose the color case colors. It took a lot of years to build up that patina, don't ruin it.

[Ballistics in Scotland]

The steel is hardened by the infusion of carbon into its outer layer, from either substances like animal charcoal or from modern case-hardening compounds, under intense heat. In effect you are turning it into a thin layer of higher-carbon steel on top of the unhardenable mild steel. But if you just let it cool slowly, it will still be soft, like a needle heated red-hot and allowed to cool slowly will be as bendable as packaging wire.

The layer is hardened by quenching in water, and is then intensely hard and brittle. Tempering consists of subsequent slow heating to remove only part of that hardness, until it shows the colour right for the application we intend. We have all seen springs, swords etc. with that beautiful full blue colour, which needs to be consistent. A sword with a harder brown spot in the middle, the best colour for some swaging dies, will break there.

In colour case hardening we want inconsistency, and it is achieved by quenching in water which cools unevenly, in ways gunsmiths often keep to themselves. They can include water full of bubbles, or binding the part loosely with wire. The parts don't need tempering because they have that tough mild steel underneath, and bend very little. But I have seen a loading lever develop fine surface crazing when it was bent cold.

I'm afraid case-hardening colours are very superficial indeed, and when they are gone, there is no way of getting them back. Some gunmakers protect them with lacquer, and it is possible that a worn surface on this lacquer will dull colours which are still present in all their glory underneath it. The lacquer can be removed with paint stripper or heat (to a much lower than tempering temperature), and replaced if you wish. Hardware store lacquers for brasswork are probably best.

[oldred]

The layer is hardened by quenching in water, and is then intensely hard and brittle. Tempering consists of subsequent slow heating to remove only part of that hardness, until it shows the colour right for the application we intend


Well no, but you are partially right.

Tempering, or drawing, is a process by which THROUGH hardened steels like tool and high carbon steels are brought back to a balance of desired hardness and ductility but color case hardening is just that, CASE hardened and it stays soft and ductile inside so tempering, or drawing, is not done. In fact trying to temper would not only be unnecessary it would destroy the coloring!

The reason carbon packing is even necessary is that the steel being cased can not be hardened by heating and quenching and will stay soft and ductile, the casing only goes a few thousandths deep so the part retains it's strength and ductility without tempering.

[oldred]

I inherited a real neat Stevens 22lr rolling block model 18 1/2. It has color case hardening on the receiver but it has tarnished over the years. Has anyone safely cleaned tarnished color case hardening to bring back some of the color? I read an article where a gent used 0000 steel wool some lubricant a real copper penny and a very light touch.


Waksupi said it best, leave the tarnish or lose the colors! Color Casing is an extremely thin layer and it's just an unfortunate fact of life that unless stored in perfect conditions the colors will fade over time. Any oxidation will take away coloring and it's very likely there are no colors left under the oxidation that you can see.

Having said that I think that Midway has, or did have, a product to help restore brightness to color casing and if so you might want to check into that as it might be of some help to bring out the coloring that's left.

[Ballistics in Scotland]

Well no, but you are partially right.

Tempering, or drawing, is a process by which THROUGH hardened steels like tool and high carbon steels are brought back to a balance of desired hardness and ductility but color case hardening is just that, CASE hardened and it stays soft and ductile inside so tempering, or drawing, is not done. In fact trying to temper would not only be unnecessary it would destroy the coloring!

The reason carbon packing is even necessary is that the steel being cased can not be hardened by heating and quenching and will stay soft and ductile, the casing only goes a few thousandths deep so the part retains it's strength and ductility without tempering.

Tempering works identically for either solid high carbon steel or for a thin carbonized and hardened layer. The reason it isn't normally worth doing for the latter (apart for preferring the varied colours) is that the unhardenable steel beneath supports it.

Once in a while someone comes unstuck by colour case hardening steel which actually is high enough carbon to become glass-hard all the way through. It will then be beautiful but very brittle. If such a part is to be load-bearing or subject to impact, all you can do is temper it the minimum you think will be feasible, and hope that the colours don't get evened out too much.

There is another process, cyanide hardening, which was used on Harrington and Richardson shotguns among others. This can be done totally unevenly, but the way they did it, it tends to be rather harsh and regular, in a pattern of lines as the part either went into or came out of the cyanide bath. I don't know what this did to the steel, but it is worth checking out whether it did produce a pattern of different chemical compositions. If so it just might be refreshable by slow and watchful hardening.

[pietro]

.

I've restored/cleaned real case colors (not the applique or chemical case colors many modern guns have) somewhat via a wipedown with a mild solvent (like rubbing alcohol), then hitting the colors with liquid cold blue (Brownell's .44-40, below), following the cold blue directions on the bottle (which include oiling the surface afterward).


http://www.brownells.com/userdocs/products/p_082440002_1.jpg

[oldred]

Tempering works identically for either solid high carbon steel or for a thin carbonized and hardened layer. The reason it isn't normally worth doing for the latter (apart for preferring the varied colours) is that the unhardenable steel beneath supports it.

Once in a while someone comes unstuck by colour case hardening steel which actually is high enough carbon to become glass-hard all the way through. It will then be beautiful but very brittle. If such a part is to be load-bearing or subject to impact, all you can do is temper it the minimum you think will be feasible, and hope that the colours don't get evened out too much



Yes but you are talking about two different things, in the first paragraph you are making the same point I did. For case hardening drawing/tempering is not done because, as you point out it would soften the case hardening the same as through hardening, and is not only not necessary but causes the loss of colors for color casing and some loss of desirable hardness for case hardening in general. When only case hardened the structural part is going to remain soft and ductile regardless.

In the second you apparently are talking about case hardening a steel that already contains ample carbon to harden so these steels should not be cased in the first place, at least not for any place where high stresses are to be encountered. Casing high carbon steels with the addition of extra carbon accomplishes little and is rarely done except for special circumstances since the required drawing/tempering step to achieve the core strength of the part will render the case pretty much useless. Besides if the part has been color cased drawing/tempering would erase the colors while accomplishing nothing except to somewhat soften the case which is undesirable also!

[Der Gebirgsjager]

Try what pietro said. It has also worked for me. The colors are a very thin surface layer, and the "tarnishing" you observe is doubtless the beginning of a fine rust. Removal of the rust will remove the colors.

[oldred]

.

I've restored/cleaned real case colors (not the applique or chemical case colors many modern guns have) somewhat via a wipedown with a mild solvent (like rubbing alcohol), then hitting the colors with liquid cold blue (Brownell's .44-40, below), following the cold blue directions on the bottle (which include oiling the surface afterward)


This is interesting, could you describe the process you used?

[Der Gebirgsjager]

No problem. Pretty much exactly as he said. Degrease the surface, put on the cold blue (I've used Oxpho), let it sit a bit, and oil it. It's not going to restore the colors to "like new", but where they have started to wear and fade they'll be filled in with blue and where they still exist they will seem enhanced a bit and the overall appearance will be noticeable better.

Another tip--after the oil has sat for awhile and kind of cured the cold blue--couple of hours, then wipe it off and coat the surface with a carnauba wax. When that dries a bit buff it off with a soft cloth and things will look even better.

[Mica_Hiebert]

What about polishing with oil and a cotton cloth and a little elbow grease?

[pietro]

No problem. Pretty much exactly as he said. Degrease the surface, put on the cold blue (I've used Oxpho), let it sit a bit, and oil it. It's not going to restore the colors to "like new", but where they have started to wear and fade they'll be filled in with blue and where they still exist they will seem enhanced a bit and the overall appearance will be noticeable better.

Another tip--after the oil has sat for awhile and kind of cured the cold blue--couple of hours, then wipe it off and coat the surface with a carnauba wax. When that dries a bit buff it off with a soft cloth and things will look even better.



Exactly......... but, please realize that there are/were different methods of achieving case colors, so the various different types will react slightly differently from each other to the cold blue solution.

I cannot tell the type in advance, so the results are what they are.








What about polishing with oil and a cotton cloth and a little elbow grease?




IME, the case colors will abrade & fade a little more.



.

[Walter Laich]

modern gun case hardening is the reason I've never messed with my Ruger Vaqueros' colors. Not sure if I had to do it over again would go for all blue or the mock-case hardening; though back then there wasn't a choice

[thegatman]

Check with Turnbull. Google website. Pricey but will get the job done.http://www.turnbullmfg.com

[smokeywolf]

No problem. Pretty much exactly as he said. Degrease the surface, put on the cold blue (I've used Oxpho), let it sit a bit, and oil it. It's not going to restore the colors to "like new", but where they have started to wear and fade they'll be filled in with blue and where they still exist they will seem enhanced a bit and the overall appearance will be noticeable better.

Another tip--after the oil has sat for awhile and kind of cured the cold blue--couple of hours, then wipe it off and coat the surface with a carnauba wax. When that dries a bit buff it off with a soft cloth and things will look even better.

Bluing, case colors and rust are all a form of oxidation. Anything that removes one will also thin or remove the others.

I do as Der Gebirgsjager mit the wax. Except I use Renaissance Wax.

[pietro]

modern gun case hardening is the reason I've never messed with my Ruger Vaqueros' colors. Not sure if I had to do it over again would go for all blue or the mock-case hardening; though back then there wasn't a choice


You made the right decision, regarding your Vaquero; as most modern guns, especially Rugers, are "case colored", and not "color case hardened".

Real case color hardening is achieved through heat judiciously applied onto a surface that's been treated with any of several different methods (to achieve the desired case colors), in a heat-treating oven (kiln) with different materials (like bone) burnt in the kiln at the same time.

AFAIK, the "modern"/Ruger sguns are chemically coated to look like real/true case color hardening, and there's no way to restore any damage to the finish/colors, short of stripping & re-finishing.


.

[smokeywolf]

Dad was a fairly well thought of gunsmith in SoCal from the late '40s through the early '60s. He did a little color case hardening in his shop. Used potassium cyanide in the mixture and quenched in a bucket of water with a couple of different types oil floating on top and a air stone at the bottom of the bucket producing agitation. Don't know what exactly he used for his carbon source, but I think bone was one of them.

I remember him saying he only did maybe a dozen parts, as the cyanide was too stressful to deal with.

[oldred]

Vaquero; as most modern guns, especially Rugers, are "case colored", and not "color case hardened"

That also was my understanding of the Ruger Vaquero, they have a chemically applied case color that is not real color case hardening. The strong alloys used in the Ruger revolvers normally can not be case hardened as they are through hardening steels that must be tempered after hardening unlike case hardening which remains soft on the inside and has only a hard layer or "case" on the outside. Alloys such as 4140 etc are normally considered non-case hardenable since they harden all the way through instead of just a thin surface layer, as such color case hardening can't normally be done and that's why Ruger uses the chemical method which is cosmetic only.


Now having said that, as Gatman mentions there is Turnbull who does indeed color some alloy steels but whatever process they use is a guarded secret that they refuse to share, whatever it is they do it's highly unlikely to be normal case hardening as we know it!

[Der Gebirgsjager]

I'd heard about the way Ruger was coloring their frames, so opted for the all-blue version. Here's a comparison to a Uberti, which I believe is colored in the old time conventional manner using bone charcoal. It is my understanding that Mr. Turnbull uses the cyanide and air agitation process. He certainly gets some brilliant colors. Few gunsmiths will use cyanide because it's deadly if not handled with great caution. Of the two, below, I prefer the Uberti, perhaps an older obsolete design compared to the Ruger, but in this case a much better shooter.
167849

[oldred]

It is my understanding that Mr. Turnbull uses the cyanide and air agitation process

They do for color case hardening of low carbon or softer steels but for coloring of alloys such as 4140, 4150 etc that won't work, at least for conventional methods anyway. They will do some high strength alloy parts and receivers but some they will not do, whatever their methods they use on those steels they won't say but I have seen pics of a color cased Ruger no.1 so for sure they can do certain high strength receivers. I think that those are considered on an individual basis and the customer must discuss their particular application before they will agree to doing the job.

[roundgun]

Thanks for the replies gents. I am going to start slow with just oil and soft cloth, and finish with wax. with any luck I may revive some of the color I can still see. I might still give the cold blue a shot.

[oldred]

Well since this thread started I tried the cold blue trick on a faded Colt New Frontier frame and I'm happy to say it does indeed do what these guys suggested it would! I would recommend approaching slowly and just use a cotton swab to dab small areas, it should quickly become apparent what areas will benefit and by how much just don't overdo it. It sure perked up that little Colt revolver, thanks guys for the suggestion!