Some Gun Bluing Shop Problems & Solutions

A. Hi, I have been telling since 2013. I use Oxynate 7 from Brownells. I am not as familiar with the chemicals you use as you are so, I can't explain your particular problem. I would switch to Oxynate 7. I know all these chemicals are expensive. But, it is a chemical you can add to the mixture if it weakens

         
Duracoat is also a great firearm finish. It is a spray-on but made for firearms; has to be sandblasted off. These are all duracoated then hydrographically dipped. That is my speciality but I did start with hot factory rebluing in 2013 and reblued barrels for a gunsmith in Maine during the winter for 2 years

A. Your gun will not accept bluing because it is made out of nickel steel, not regular gun metal. There are a few guns that are made out of nickel steel and they have to be sent back to the factory to be redone. You have a very good gun, it is old and valuable and kind of rare. It would be worth putting the money into.

A. We blue nickel steel in our shop, with Oxynate No. 84 [affil links] with great success.

A. You have just discovered one of the facts of life, not all steels will blue with Oxynate 7, you can do one of the following, iron plate the receiver, then blue, get some Oxynate 7., or just Parkerize .
the whole thing, (this is the easiest answer)

A. Old Win 94's have a multi alloy steel receiver different then the barrel. The receiver is actually painted and baked in high temp at the factory and the barrel is hot blued. I have used a lower temp in the bluing tank for the receiver and carded the receiver with hard brown paper and comes out decent. Lots of trial and error

A. Amjad, do a search for 'gunsmithing" sites. There are kits available that have all the chemicals for cold bluing and the instructions. With any bluing, you still need to oil the metal after bluing to prevent rust.

Good luck,

Still, cold bluing is NOT more corrosion-resistant than hot bluing; it's slightly less so. It's the wax or oil which is applied that provides the corrosion resistance.

Doing a better job at home than the professionals can do in their fully equipped shops doesn't sound likely, sorry. Good luck trying ... but the critical thing is keep it oiled! :-)

Regards,

A. Hi, Willie. The likely problem is that steel rusts quickly (flash rusting), accentuated by the bluing solution being acidic, and the bluing adds no corrosion protection. The gun has to be neutralized -- dipping in dilute sodium bicarbonate/ baking soda [on eBay or Amazon] will help -- then oiled or waxed immediately after bluing, and frequently thereafter. As Ed implies, it's orimarily the oil, not the bluing, that deters rusting. Good luck.

Regards,

A. This is a rinsing problem.

If random orientation as you state, then some parts will have the blind hole up during processing. The black oxide solution is much heavier than water, and will not likely rinse well, some will remain in the bottom of the hole, and will cause the problem you describe. How difficult would it be to orient parts so the blind hole is horizontal during processing? This would likely allow adequate rinsing. Any additional agitation you can provide during rinsing will help too.

Q. Jeff,

In years gone by, the bluing department has put the parts in racks. The were oriented hole-down. The problem was that they'd fall off in the process, somewhere between all the tanks. With the exception of the hot/cold oil, the other tanks are turbulent. Another problem was the fact that thousands of these parts are done at one time. The logistics of setting up these racks was not good.

It may be worth considering a longer rinse cycle for these parts. I just received another batch today that had about 10% with bluing salts in the blind holes. Some of them were so bad that it looked as if it was intentionally packed in. These parts had sat in stores for 2 1/2 weeks. It has been relatively dry here, so humidity has not been a factor.

Still plugging away...looking for corrective ideas!

John

Maybe longer rinse cycles will help, but I'll bet that you have a continuing problem with those parts which are processed with the hole upward. The black oxide solution is heavy and viscous, especially as it cools down.

While I don't know what the part looks like, I'd think one could spend a few dollars for a purpose-designed processing basket which would orient the parts with the problem hole horizontal. Loading parts into such a basket could certainly be done at a rate of thousands per hour, a very small labor cost.

If you're processing thousands of parts, and producing hundreds of defective parts, I don't see how that can be acceptable. Doesn't it cost a lot to rework the defective parts? Do defective parts interfere with assembly efficiency? Do some of them make it to the customer? What does all that cost in comparison to doing the job right in the first place?

A. Any possibility to drill the blind hole all the way through? Maybe a smaller through-hole if the bottom is important.

A. Well you haven't given me much to go on here but I suspect that you have a transition gun. When the manufactures made the jump from 38 to 357 magnum and especially duty guns that had to be kept light the manufactures some times went to nickel steel to beef up the strength of the cylinders to handle the higher pressures of the 357. I doubt it is stainless as I have never heard of a manufacturer mixing and matching steels although I don't doubt that it has taken place. Nickel steel can be a bit of a pain in the butt to blue and there are salts made just for that which make things simpler but most often common garden variety salts will work with a bit of coaxing. What you might try to do is add a bit more niters to your batch and bring the temperature up to the very maximum. Shocking, going from the blue tank to the cold water repeatedly may also help. Most of the old 1894 Winchesters have nickel barrels and I have yet to find one that I could not blue. There is a simple test you can do first. If cold blue stains it, its not stainless steel. If cold blue won't touch it find some one that blues stainless or polish it to a high finish and have it black nitrated.

Q. It is an Iver Johnson 1900. I have 2 of them. One is a .32 the other is a .22 L/R. I have redone both of them. The 22 is the one I am having trouble with now. I blued both pieces at the same time. As I stated before the .22 I had to redo the second time both the frame and cylinder. Frame turned out beautiful, Cylinder did not. ( same salts bath). The cylinder did blue the first time where nickel wasn't on it. after bead blasting and polishing it didn't blue at all. Is there any possibilities that metal properties may have changed? In the mean time I'll try again. Thanks for response.

A. Well it sounds like it could be a combination of problems. The first is the steel itself. The number series of the model 1900s should blue fine. They were made of at least a reasonable facsimile of 4140. the serial range was 00001-100,000 and were made between 1900 and 1908. The D series guns D0001-D100,000 were the first run of the higher nickel guns which were made from 1909-1917. This more or less coincided with the USA's entry into world war one in 1914 and as one can imagine steel production was in a great deal of flux to keep up with pre war production. I would be willing to bet that your gun is one of the D series guns and has a much higher nickel content due to the inconsistencies in steel runs. The final series was the A series. Serial numbers A 0001-A37,000 and were made from 1918-1941 after the steel industry had gotten its second wind. The A series should like the number series guns blue just fine. It sounds almost as though your salts may be beginning to deplete. As I stated before you may have to add more Sodium Nitrate [affil links] to your bath or if you are using a commercial bath you may have to start a new batch of salts. Before doing this I would suggest trying to blue the cylinder again. This time start the bath at 280 and let the water boil off until the salts reach 310 or 315 if you have faith in your thermometers. At 295 begin shocking the part. Dunk it in cold water and then go back into the blue tank for 5 minutes and keep repeating this until the bath comes to 310 or the part blues. After the bluing does take leave it in the blue tank for an additional 15 minutes or so as the color may be slightly mottled from the shocking. Nickel steel is a pain to blue but it will blue eventually. The last case scenario is to start a new bath.

Q. Sorry for not getting back sooner. I did get the cylinder to blue. I did just as you recommended. Heat was up to @325-330. I shocked it about 7-8 times. I could start to see it blue after about the third shock cycle. It took about 45 minutes to complete. It turned out O.K. I think you might be right about the properties of metal used. There are different colors in it. Thanks again for the help.

A. The problem is Benelli uses stainless; and if it's not stainless the other problem is you are not at the right temperature. The right temp is 292 °F for 30 min. 310 °F is the uh-oh temp. 280-290 °F is not hot enough.

A. What you see is typical when a cast iron receiver is run through a standard black oxide line that is for steel. I believe the silicon content of the casting causes this specific color. In my opinion this "color" will have the same wear resistance as your barrel which of course came out black.

Some suppliers of hot black oxide chemicals make a special kind of salt which will turn the cast iron receiver black.

A. Hi Adilene. The gun probably wasn't clean or is corroded at those spots. Neither bluing nor anything else sticks well on wax, oil, grease, or dirt; and poorly adhering oxides from corrosion can rub right off, taking any bluing with them.

Regards,

A. Hi Don, oil is the whole secret -- whether it's transmission fluid or another oil. Cold bluing offers no rust resistance at all, and hot bluing offers almost none. I suspect that at some point either overzealous cleaning or time-&-tide removed the protective oil, leaving it prone to flash rusting.

Regards,

A. Hi Ali. The defect may have been random due to improper cleaning. Neither extremely hazardous gasoline, nor any other solvent-style cleaner should be the last step. Alkaline water-based cleaning must be the last cleaning step.

Luck & Regards,