I didn't want to hijack TC1's thread on rust blue, but I've often wondered when is one method more desireable than the other. I realize that from a logistics and safety standpoint, a hot (caustic) blue poses some challenges/issues, but are there any other considerations. Is one more durable than the other, etc. Please pardon my ignorance if I'm not framing the question correctly. Thanks in advance for your replies. - Brian

The below is not from personal experiences or testing-

First, you can do a search and find an interesting post on this by D'Arcy Echols a well respected gunsmith. He actually did testing and found hot bluing to be more durable.

Most people consider Rust Bluing to be the most durable, and this is well supported by the number of old guns that still look pretty darn good. The belief is that because rust bluing when done properly rusts the surface of the metal until it cannot rust any more then it is most impervious to moisture (I know, somebody just is going to HAVE to talk about stainless, that wasn't in his question so it matters absolutely not at all here).

Rust bluing is more expensive, as it is more labor and time intensive. It also is not as easy as hot bluing. Things like temp, humidity, type of water used in the boil off, type of solution, all are critical for the rust blue results. the guys that do it well and make money at it have spent a lot of time getting it right. There are a couple on the board that offer this service.

Hot bluing is easier to do, but as you said has some challenges, the chemicals you are working with, size of the setup, cost of setup etc. But a lot less learning curve.

Rust bluing works better on metal that isn't very highly polished, so you will usually get that pretty matte finish, if you want high gloss (some guys like that) then you'd want the hot blue. when using the accelerant for rust bluing it has to "bite" into the metal, the higher the polish the harder it is for that to happen and get good coverage (again, not from experience, from my pre-trying-it research).

My personal preference? On a fine custom or "classic" rifle I like the rust blue, the way it looks and the way it wears (some older rifles I have seent he blue is not there any more but they still haven't rusted in those wear spots, don't know why that is, Roger or Chic can maybe help with that). On a working rifle where budget matters I'd just go hot blue and be done with it, still look really good.

Red

I don't think that Baiar's solution was available when Echols did the tests.

I have cut engraving through rust blue and there is a thickness to it that isn't there with hot blue. I just don't see how caustic blue can be more durable than rust blue. JMHO!

rust blue
hot blue
hot water blue...
rust blue -- outside of the gulf coast, takes several days.. excellent finish... best practiced with a junk 22 to learn how to keep the rust out of the barrel


hot blue... fast, easy, durable... and COST EFFECTIVE ... which is why it's done


hot water blue... takes about 4 hours, soup to nuts... can be pretty nice looking...

jeffe's blued - brown...

use "plum brown" .. apply to pure even brown... boil it... wow, it CAN turn a nice purty blue ..

jeffe

I have used the plum brown years back. It comes out a bit course for my liking.

I have been using Baiar's Gun Goddess for about 15 years and it's the way to go.

I would question anyones test that showed that caustic bluing to be more durable than rust bluing. I can show you a quick one that will dispell that in a heartbeat. Drop some blood from the tip of your finger on each and wipe it off, the cautic bluing will be gone and the rust bluing will not be affected. End of story. Wear is just the same, take a small piece of sand paper and see how long it takes to remove the caustic bluing and then the rust bluing.

Brian, back to your question. Rust bluing is more durable by a long shot, it is more expensive and you end up with a matte finish where the caustic blue can be matter or a high shine. You won't get a high shine on a rust blue.

I just want to point out, I did not say that I thought the hot blue was more durable, just that one test had shown that. I have not done my own but like I said, there are some great old rifles that still look good.

I have Jim's solution out in the garage and was looking at my notes today on what I need to do to try it out. I am thinking about trying to blue a floorplate this weekend and seeing how it comes out.

Red

While in high school (yes high school) I had a gunsmithing class and we did the test Chic describes. he is right the caustic blue came off, or at least was distorted. I was amazed. You need to get the blood off as soon as possible, We left ours overnight though.

Red, I understood that. You were passing on what someone else said and I was commenting on his comments, not yours. Sorry if you misunderstood.

333_OKH, the same thing will happen with a weak acid. A diluted muriatic acid is often used to create "french gray" with on a caustic or rust blue. When the acid touches the caustic blue it is gone but not so with the rust blue. You use a tooth pick and rub and rub and rub to get it off. Not exactly what you would expect from something that is LESS durable. Probably because the opposite is true.

The durability of either method has a lot to do with who is doing it, and the quality of the end result. The top picture is a 1938 Brno in 8x60 that has been rust blued by Griffin & Howe. The bottom picture is a 1947 Brno in 7x64 that has a very heavy duty hot blue that was common in early post war years.

I have no intention on finding out which wears off easier.

Kurt, even if I supply the acid for free?

One thing to remember about bluing soft-soldered doubles, most were “Rust Blued†and if hot blued you can end up with separated barrels.

Kurt,
Where did you get those Leupold QR bases on your Brno?

Bill at Griffin & Howe made them for me out of a set of Leupold blank gunsmith bases. My only instructions to him were to leave the charger hump alone.

So, that really deep, royal, shiny blue of the old S & W revolvers was obviously a hot caustic blue. Anyone know of their method and salts? I had my .338-06 (a 1942 Mauser) hot blued and it came out very black and very shiny. The guy that did it called it black chrome. I like it, but really would like to know how to get that Smith and Wesson BLUE finish....

MKane160

quote:

Originally posted by MKane160:
So, that really deep, royal, shiny blue of the old S & W revolvers was obviously a hot caustic blue.

Could have been a charcoal blue.

S&W discontinued Carbonia blue in about 1985. Since then they have used caustic hot blue.

Roger, what is the Carbonia blue? I used to own a Model 17 if I remember right....I dunno, 60's production? It had the most beautiful, deep gloss blue. Was that it? How is that different from caustic or rust bluing?

MKane160

The Carbonia version was a proprietary process that was heat treat type blue. The parts were installed in a rotary retort furnace. The parts were held static while the furnace rotated around the parts with leather and bone charcoal mixed with some type of oil (Possibly sperm oil) that would spill over the parts. The very early M70 Winchesters were also blued this way. They quit that type of blue because people were complaining about the glare. When caustic hot blue became available they made the switch and sand blasted the receivers.

The operator has a lot to do with the quality of hot caustic bluing also.

Surface prep. is everything and water quality have a lot to do with the final product as does what you do when you drag the piece out as the curing process is there also.

A big thing I've found doing this for 16 years is that most operators when they plop the piece in will leave it in for their required period of time to produce the "color" they want.
The good ones will put the piece in and look for color and then pull and rinse the smut off, then continue doing this every 5-6 min.

It takes longer and is more labor intensive this way but the end result is well worth the effort in all catagories.

JM$.02

Don

quote:

The guy that did it called it black chrome

Are you sure it wasn't? This was a popular process at one point in time for hard used guns. Charlie Askins seemed to have every gun chromed in and out and used a black chrome process from a firm in Florida if I remember right.

Is charcoal bluing remotely feasible for the hobbyist, or is it as complicated as it sounds?

I got the info from S&W. Wisner's sent me back to Smith in the mid '80's for their armorer's course, then on to their service deptartment for more warranty work training. The service deptarment is where they put all the old hands that know the in's and out's of all the models. Novel approach, don't you think. The youngest guy in there had been working for Smith for 25 years. The training is done by setting you down in the midst of these guys and repairing/rebuilding guns that come in. You get a lot of bullshit time when working in that atmosphere. We talked a lot about different models and processes of manufacture. The bluing precesses employed being one of them, as that was my other duty while working at Wisner's. I didn't do any other checking on the subject, but assumed they knew when they went to caustic blue. Do you have information otherwise?

Yes, I've used Cullity a few times. I think that Dan mentored Turnbull in the process. Dan's work is impeccable, but I believe that Turnbull's colors are closer to the old Colt and Winchester finishes.

Drop me a note if you find out different about my timeline with Smith's metal finishing processes.

While on the topic of metal finishes, can anyone tell me what process Savage used for the early 99’s, say up to the 1950’s?

- stu