Neat Rust Bluing trick

[oldred]

WARNING!!!!!! I have only begun to experiment with this and although it looks promising it still may need to stand the test of time!


A friend of mine was showing me a Marlin 336 he had blued and it looked great! He explained that he had cold blued it first (I forgot to ask the brand but it was a simple cold blue from a bottle, not the higher tech Brownells stuff) then followed that up by heating it with a heat gun and doing three cycles of the Mark Lee Express Rust Blue process. Even in bright light this thing is stunning with no trace of streaking or light spots and it seems to be as tough as normal rust bluing, he rubbed it vigorously with steel wool without changing the hue in the least. This was after only three cycles of the Express Blue process but he told me that even the first application looked nearly as good as the finished project, I am not sure I would want to do an entire gun using this method but it might just be a real trick for doing small parts.

So far I have only experimented on one part, a hammer for a cheap single shot shotgun, I polished to 320 grit then heated the hammer with a heat gun and applied the cold blue. I followed this immediately by re-heating and one application of ML's Express Blue then boiled in distilled water, ONE cycle and the darn thing looks finished! I have a very fine wire wheel from Brownells made just for rust bluing and using this I buffed the dickens out of that thing and all it did was polish it. I followed up with 0000 steel wool and rubbed it to the point I am sure cold blue would have been completely removed but it still looks good after all this.

I don't have a clue why this seems to work like it does and I may be "jumping the gun" because it may be too soon to say for sure but this looks really promising (for small parts anyway)!

[country gent]

While I have little experience with rust bluing we did alot of parts at work with cold blues. The birchwood casey soulution they purchased did seem to work better if part was cleaned and soaked in hot water for 1/2 hour to 1 hour to warm it thru first before dipping in solution. What may be happening here is the cold blue is getting the metal prepped and the right start for the rust bluing to work and allowing it to work with out the normal surface impurities. Sort of a final clean and prep getting molecules ready to color and accept it.

[John Allen]

I am going to try this over winter on a cheap 22 I have.

[oldred]

I don't pretend to know what's happening but it sure seems to work pretty well. I just tried a 2"x3" scrap piece of flat 4140 alloy, wide flat areas like this (think the receiver sides of Winchesters and Marlins) are a PITA to get evenly colored tending to be streaked in bright sunlight even if they look good in more subdued lighting. After only a couple of cycles this piece is already much darker than usual and very even, I am going to give it a couple of more cycles then buff the dickens out of it to see what happens.

[oldred]

Well I just tried something that does NOT work! I took some G96 cold blue and applied it to a part that had been rust blued first (no cold blue underneath) to see if it would darken it and/or eliminate streaking, the darn stuff destroyed the rust blue! I at first thought this was working really good but then I rubbed some dark spots that had formed and the bluing at those spots simply disappeared all the way down to bare metal, this rust blue was about 5-6 cycles (don't remember for sure) and about two days old so I don't know if maybe it was not properly cured (or even if rust blue cures over time???) but I would have thought cold blue could be used to touch up spots on guns that have been rust blued?


BTW, all this is being done on pieces of 4140 I have in the shop and not actual gun parts.

[nekshot]

thanks, i'm gonna try that!

[leftiye]

Not on topic, but old guns with a brown patina (do NOT do this to collectors where the patina is worth dollars!) When blued with oxpho blue result in a browning. It's not real uniform, but when used in a touch up situation, it does greatly improve appearance.

[oldred]

While on the subject of touching up old finishes, after I got that little surprise that the G96 ate away the rust blue when I applied it over a two day old finish I decided to try it on something older. I picked out a spot on the underside of a single shot shotgun barrel (under the forearm) and dabbed some of the G96 onto it and rubbed it in (after degreasing it) much the same as someone might if repairing a scratch. It was the same as the test piece, at first it looked as if it would work just fine then suddenly a few very dark irregularly shaped spots appeared and when these were wiped away it took the finish off all the way to the metal -total destruction! This finish is about two years old but it did the same as the the two day old finish so I'm thinking that maybe rust blue finishes and cold blue are not compatible, if touching up a rust blued gun with cold blue I would be VERY careful and only lightly rub on a really light coat of the stuff.

I would really like to hear about others' experiances with touching up rust bluing.

[johnson1942]

thanks for the post old red. i have a barrel i just took off a gun that was cold blued and i wanted it better. i will try the rust blue on it over the cold blue. what is a heat gun? sounds better than trying to stick a barrel in the oven.

[thekidd76]

How about a pic of that hammer oldred?

[oldred]

what is a heat gun?


It's basically a hair dryer on steroids, it heats to over a thousand degrees and will overheat small parts in short order if you're not careful. 15 bucks at Harbor Freight and I would be lost without mine, it is a much used tool around my shop!

http://www.harborfreight.com/1500-watt-dual-temperature-heat-gun-572-1112-96289.html




Kidd, I will try to get some pics up but I have already installed the hammer, I especially would like to get some pics of that Marlin that got me started with this. It might take a day or two before I can get to it but that darn thing looks really good and he said it only had three cycles of the Mark Lee Express blue over the cold blue, I will get up with him and try to get everything he did along with what brand of cold blue he used.

[rking22]

Very interesting, I just bought the most miserable little M36 smith you could imagine. It had been painted to hide the finish(lack of). Got it cheap, and it shoots great. Gonna try this on it instead of just a plain rust blue. "Adjusting" the sights will keep me occupied till he final details are divuldged :)

[Cactus Farmer]

Why is "cold blue" called that? It works soooo much better warm. Warm blue doesn't sound good I guess. For me, it sometimes seems the type of steel or the heat treat can make the finish change. More applications usually fixes the problem.

[vasecho]

Cold Blue is called cold blue as it does not require hot water baths ect and can be applied without Heating , Boiling, specialized equipment.

That being said every chemical reaction can be "sped up" with the increase of heat.

The secret that people forget is that Bluing liquid removed Bluing so to clarify that statement - when you apply a coat of bluing and it dries is chemically reacting but if you apply a puddle of bluing its a circle reaction of it trying to apply then removing itself then trying to apply. (i hope this statement is understood as im trying to avoid going into the actual chemistry stuff here and stay layman)

With the small amount of heat it applies dries and sticks more quickly and is a more efficient reaction. In the shops i work at we always teach the young guys to run it under hot water till warm, blue then run it under hot water to stop the reaction.

so test this all you desire but imho this info is the way to do it

[KCSO]

This is like the old browning trick of using a coat of Plumb Brown first. It gets the metal started and gives the rust a good first bite. I have been doing this for about 20 years and have not had a reject yet.

[fouronesix]

This is like the old browning trick of using a coat of Plumb Brown first. It gets the metal started and gives the rust a good first bite. I have been doing this for about 20 years and have not had a reject yet.

^ second to that- works very well!

Plum brown works well on properly heated steel, if applied correctly. If desiring blue-black then, once the plum brown is even and set, it does take and enhance any of the cold blues.

[oldred]

Ok fumble fingers just accidentally deleted an E-Mail while trying to reply and since I was unable to recover it I will try to answer here,

By "cycles" I mean the entire process of heating, applying the solution, allowing to rust and then boiling/carding. Also applying cold blue solutions to the rust blued surface has resulted in total disaster for me, I attempted to "darken" the rust finish with cold blue after about 4 or 5 (I don't remember exactly how many) applications of rust blue but the cold blue solution just stripped the rust blue off. It appeared to be working at first but then as I rubbed it some more it simply ate into the rust blue and stripped it off. It seems as if it works quite well to apply the cold blue first then proceed with the rust bluing but once the rust blue process has started it's best to put away the cold blue bottle!


Once again, approach this with caution as I have only done some experimentation here and while it does indeed seem to work quite well there very well could be some as yet unforeseen factors that could cause major failure! I intend to delve a bit deeper into this method when the weather gets colder and I can't work outside for a while, I intend to try several different brands of cold blue and maybe I will be able to refine the process somewhat. It does look promising right now and so far I have been able to achieve some deep coloring with just a few rust blue applications, time will tell I suppose.

[leadman]

A friend of mine is in gunsmithing school and he rust blued a Savage 24 of mine for a school project. It did not want to stop rusting so I went over it with Brownell's Oxpho Blue. It did not harm the finish, deepened the color a little, and no longer rusts.
The OP results might be specific to the brand of cold blue he used??

[oldred]

That's interesting about the Oxpho Blue and I have been wondering about that very situation. Almost all cold blues are just a variation of the same chemicals but Oxpho Blue is very different according to Brownells, I have been intending to order some and your reply has cinched it!

BTW, if the rust blue your buddy did for you did not stop rusting then he failed to neutralize the acids, it's a VERY good idea to rinse a finished rust blue project in hot soda water before oiling, dissolve as much baking soda as the water will absorb then with the water/soda at least quite warm (the hotter the better) just rinse the parts, dry and oil. This will easily solve the after rust problem.

[mazo kid]

I'm assuming you were attempting to answer my email. It's just as well you accidentally deleted it, because now we all benefitted. Strange that the cold blue- rust blue process works but not the other way around.

[DougGuy]

I do a lot of cylinder throat reaming, the trick I learned is to mix the Oxpho Blue (Brownell's) paste and liquid 50/50, and clean the cylinder after reaming in hot soapy water, hot water rinse and compressed air blow dry, then I put it in a toaster oven until it is a little too hot to hold with the bare hand. About 300° I am guessing. After using a q-tip to put bluing inside the throats 2 or 3 times and swab it around, then finish with hot soapy water and hot water rinse. You can't tell it isn't blued from the factory. I don't do the whole cylinder, just the inside of the throats. Makes the finished job look very professional..

[waksupi]

When we would get a shipment of AK's in from overseas, they would be crawling with rust salts. We would get a can of soda from the pop machine, wash the parts with it, and all the salts were neutralized. The boss thought I was pretty smart for once, knowing that.

[Blackwater]

This is a very interesting thread for me. I've used cold blue in the distant past, but never had any good results from it. I learned to appreciate Oxpho Blue from a gunsmith buddy. My experience is it is MUCH better than the cold blues, regardless of manufacturer. I've also used the Mark Lee Plumb Brown and done bluing. All it takes to get any good browning job done, at least in my experience, is to heat it beyond the boiling point of water in the rinse, and it'll turn a nice deep shade of blue-black. It's basically, at least as I understand the chemistry of it, a hurry-up method of rust bluing. I've read that the old A-5 and other Brownings (the ones made in Belgium) were blued by the "hot water blue" method. Thus, their insides were plain metal with no bluing internally. One way to tell if a Browning from that era has been refinned is to see if it's blued internally. If so, it's almost surely been reblued. I've found Mark Lee Plumb Brown to be plenty sufficient without the underlying layer of cold blue, but it's still interesting to see these reports anyway. The real trick to ANY bluing is of course, the polish job and how diligent you are in applying the bluing, heating and rinsing, etc. Just the right temp turns most any brown to blue. Wish I knew more of the exact chemistry, but heat seems to be the catalyst in turning it blue. It sure does make for one fine finish if attention is paid all along the way. It's not for the casual hobbyist, though. It can be pretty exacting in my experience.

[oldred]

. I've found Mark Lee Plumb Brown to be plenty sufficient without the underlying layer of cold blue

That's a very good point and I guess I neglected to mention at the start of this thread that a properly done rust blue, even the "express versions" really stands on it's own and is probably one the best toughest finishes a firearm can receive and it really does not need any "help". The reason I did this was twofold, one it seems to reduce the number of cycles required to obtain a nice appearance but also, and the main reason, is that it seems to all but eliminate streaking and the brownish "background" hue that can be seen under some rust blues in bright light.

The project that started this was an old Marlin 336 that turned out really nice and both the owner and I were quite happy with the results, BUT in bright sunlight on the receiver sides a a brown/reddish hue could be seen under the blue. Turns out this is not at all unusual and apparently it's used as a method of identifying a rust blue finish when examining a firearm, not sure of the exact procedure but a bright light is used and sometimes even a magnifying glass. First off let say this is NOT a problem or a flaw with the rust blue method, if a person has to resort to exceptionally bright lights and even a magnifying glass to see this then it can hardly be considered a flaw! In the instance of that 336 it was in all likelihood a simple case of stopping the rusting process a couple of cycles too soon and had I continued it probably would never even have been noticed, in any case it was so minor neither of us was the least bit concerned -well maybe I was a bit concerned and that brings us to this thread! Working with small 4"x4" flat metal pieces I started to experiment with the cold blue/rust blue process and I discovered two things, the number of cycles needed to get a nice coloration was reduced and that brown/reddish background was eliminated. Before tackling an expensive gun however I intend to experiment some more to determine what effects this is going to have on wear resistance, long term color holdout and rust resistance but so far the results have been promising.

[mazo kid]

Is the Oxpho-Blue and Mark Lee Express Blue available anywhere else but Brownells? I don't want to appear cheap, but I was going to order those products from Brownells; $22.00+ for the 2 items and $18.00 shipping. Really? For a package weighing less than a pound!

[oldred]

I think these are considered Hazmat materials so there is an extra shipping charge. BTW the Mark Lee Express Blue is really good stuff and I think you are going to like it so unless you are just planning to do one gun you might want to go for the big bottle. While the little one will usually do more than one gun the difference in size of the container vs the price amounts to a HUGE difference in cost per ounce!

[mazo kid]

Thanks, I may just have to "bite the boolit" and order these items. I really would like to try them.

[Billthomas]

I helped a friend redo a Luger that he was having problems with and we used alternate applications of cold blue and a weak hot salts bath, the results were so close to original finish it was scary. Can't explain it, and only tried it as a last resort. It may be the high temps making the cold blue solution work better Bill T

[oldred]

It may be the high temps making the cold blue solution work better Bill T


It could be but the first experiment I did with cold blue was to boil it as if it were rust blue to see what would happen, not much as it turns out, it was decidedly darker but no more durable at all. Now having said that I realize that hot salts blue is MUCH hotter than just plain boiling distilled water so that could very well make all the difference as could possibly a difference in brand formulation.