nickel refinish to other ?

[bamaranger]

Can a S&W nickeled revolver barrel, be refinished to matte blue, or perhaps recoated with something like Black T with satisfactoy results?

[Bill DeShivs]

Nickel can be stripped to bare metal, then the part can be blued.

[James K]

The best way to strip a nickel plated gun is to have a plating shop reverse the plating process electrically. I have had guns stripped that way and the result has been very successful.

Jim

[Dixie Gunsmithing]

Jim is correct, reverse plating is the best way, especially for bluing after.

[Bill DeShivs]

There are chemical strippers available that work very well.

[psalm7]

We used a deep cycle battery and very heavy cables to reverse plate . Put the firearm connected to one cable and a pice of metal connected to the other in a tub of chemical .
I donot remember ths chemical our wich terminal to connect the gun to to reverse plate it . I just posted this limited info to show you could do so without a lot of high tech stuff . Its been about 30 years since I did this process . After strippnig buff then blue .

[Dixie Gunsmithing]

The electrolyte is battery acid, (sulfuric acid). You mix it with water, the same as you do for a battery.

Electrons flow from negative to positive, so to plate something, you make it negative, and to deplate, you make it positive. In doing this, the nickel leaves the gun, and is collected on the cathode. The problem is, that the electrolyte will have some free nickel floating in it, so you can't use it for anything but nickel plating afterwards.

[Bill DeShivs]

Plating and reverse plating (electrostripping) is not done with sulfuric acid!
Electrostripping will also remove the underlying steel, so you have to be careful.

[Dixie Gunsmithing]

Bill, battery acid is sulphuric acid. Its the same stuff used in a lot of electroplating, at an approximate 15% mix with water. I use it in anodizing, and buy it at an auto parts. You can use Chromic or Boric-Sulphuric, however everyone mostly uses plain sulphuric. Muriatic wont work, as it will eat aluminum.

On nickel, they use Boric to plate, but Sulfuric will work for stripping. Sulfuric is used to adjust the pH of a Watts bath using Boric acid. So it becomes a Boric-Sulfuric. Boric is used for nickel plating to control it.

Anodizing:

The sulfuric acid process is the most common method for anodizing. The sulfuric acid anodize process films range from .0001"-.001" thick. The overall thickness of the coating formed is 67 percent penetration in the substrate and 33 percent growth over the original dimension of the part. It is particularly suited for applications where hardness and resistance to abrasion is required. However, where parts are subjected to considerable stress, (such as aircraft parts), the possible presence of the corrosive acid residue is undesirable. The porous nature of sulfuric acid films prior to sealing is used to particular advantage in the production of colored surface finishes on aluminum and its alloys. The porous aluminum oxide absorbs dyes well, and subsequent sealing helps to prevent color loss in service. Although dyed anodized films are reasonably colorfast, they have a tendency to bleach under prolonged direct sunlight. Some of the colors are: Black, Red, Blue, Green, and Gold. For defense/military and homeland security applications, Anoplate offers olive drab green anodize, urban gray anodize and black anodize. Parts can be treated chemically or mechanically prior to anodizing to achieve a matte (non-reflective) finish.

Link:

http://www.anoplate.com/finishes/anodizing.html

Watts bath and sulfuric acid:

The pH should rise slowly during operation, since cathode efficiency is slightly lower than anode efficiency. Sulfuric acid should be used for pH adjustment, although hydrochloric acid may also be used with the added advantage of maintaining the chloride ion concentration. However, the disadvantages of using hydrochloric acid include not only the higher amounts required but the escaping hydrogen chloride gas, especially from a hot, air-agitated solution

http://www.pfonline.com/articles/nickel-electroplating

[bamaranger]

OK

Thanks all

[Unclenick]

The problem of attacking the steel underneath is real enough. A super low voltage (on the order of a tenth of a volt) cell with a nickel salt solution could do the job safely, though it would take hours or even days to finish. The sulfuric acid baths and higher voltages are used by commercial operations because of their greater speed, and they need to have their tanks make money rather than tying them up with slow speed work. They do, however, typically use additives to help protect the substrate metal from being attacked aggressively. Still, they have to watch the job carefully to see that removal doesn't go too far.

There is a good description of a process in post 11 on this board. He recommends not exceeding 6 volts for reasons of consistency (mentioned in post 13). You can get 6V deep discharge batteries for golf carts, which often use 6 of them in series to make up a 36V bank. He also uses a stronger acid mix. From other reading, this should avoid removing nickel too much faster from sharp edges nearest the cathode than from inside corners (it's a better throwing power solution). He recommends using a lead cathode. I would not have the parts too close to the cathode, also, to help minimize preferential removal of the nickel from the surfaces nearest the cathode. The smaller the difference in distances between plated areas on the part area are as a percentage of the total distance from the cathode, the less trouble with uneven removal rates you should have.

[Dixie Gunsmithing]

Unclenick, I use 5 volts, so that's close. However, I use a regulated supply, and control it by setting the current side, so it doesn't go over that amount. I have seen some do this using light bulbs, as current limiters, but I'm not sure how well that works.

If plating, you have to worry about the finish, and they use the Boric acid to keep the nickel from forming lumps, that turn green. They mix it with sulphuric acid to adjust the pH through the process.

On reverse plating, you don't need to worry about the looks of the cathode, so you can get by with sulphuric acid and water alone. The acid is thin enough, with the water, that it's not that hard on the steel. One still has to watch the process, though. Purchased battery acid, or sulphuric, is about 30%, but you cut that in half. Brownell's was selling it in powder form, to neutralize bluing salts for disposal. How well one could use that, I'm not sure.

[Bill DeShivs]

That's really interesting!
None of my nickel plating solutions contains sulfuric acid.

[Dixie Gunsmithing]

Bill, The main reason they use Sulfuric is it has about the highest conductivity when making up an electrolyte, and is why they use it in lead acid batteries. However, it doesn't play well with nickel by itself, or the nickel anodes available, so they use Boric with it. Boric acid is a weak acid, but chemically, it works with the nickel better, however, they adjust the pH level with Sulfuric in large baths, and one can probably use Boric straight, with water, though the plating time will be longer. You can do it in reverse too, but how long it would take, for Boric, I'm not sure. In the plating houses, they call the mix of the two Boric-Sulfuric.

One could buy Boric acid at the pharmacy, but I'm not sure of its strength, nor if they still carry it in these chain store pharmacies anymore. I buy Sulfuric from NAPA auto parts.

On the mix, I mix it about 1/2 to 1 with water, if its 30%. I check it with litmus paper, for a red coloring in the range between 3 and 4. Straight out of the bottle, it is a 1 to 0, (at the scales end), or dark red on the paper. I think the guy in the link said he mixed it a little stronger, or 600 mL to 1 L, which is a little over 1/2 to 1.

[Bill DeShivs]

I just buy commercial nickel plating solutions. They don't contain sulfuric acid.

[psalm7]

I do recall one gunsmith I worked with that was removing the plating from a S&W pocket pistol that set up a large glass container and a battery charger for the process to save the trouble of setting up all the other stuff we used on larger jobs . Not wanting to get off topic but is muratic acid still avalible ? We used it to get oil out of badly oil soaked wood on vintage and Military surplus firearms .

[Dixie Gunsmithing]

Muriatic acid is Hydrochloric acid, and may work on steel, but I wouldn't get aluminum around it, if it has any strength. Also, you'll need it strong enough to mix with water, to get the right pH for it to work. Last, there's some bad fumes that will be generated from Hydrochloric.

[Unclenick]

Incandescent light bulbs do keep current from increasing in proportion to voltage, but it's not a constant current, but closer to holding current down in proportion to square root of the change in voltage. So it works to limit current to a degree, but it's not truly constant. You used to find lamps used for this purpose in old vacuum tube equipment. I imagine some 12V car lamps would handle the current over a useful range.

The now discontinued Outer's Foul Out worked by the low voltage limit method, but it would take 2 to 4 hours to finish working. The patent described a 0.3V limit on copper removal and 0.25V on lead removal. They used a mix of copper acetate and ammonium acetate in solution for copper, and lead acetate and ammonium acetate solution for lead. Looking at cell potentials for metals, I think this would have to drop to 0.1-0.15 V for nickel removal and nickel acetate would be needed in the solution instead of the acetates of the other two metals.

Someone wrote an article about a unit using ammonia and 3V to remove copper fouling, which seemed to work for stainless barrels, but someone who tried it on a plain steel barrel got after-rust a week later that looked like he'd fired corrosive primers and left the gun in a humid area. So you have to watch what you are doing.

Sulfuric acid is a liquid above its melting point, which is 50°F (10°C), and there is no powdered form possible until you have it all crystalized below that temperature and keep it there. However, some folks use sodium bisulphate powder in water to get sulphate anions, and it is also a corrosive acidic solution. So it is sometimes substituted for actual sulfuric acid where you only need the diluted acid, as in this case.

Hydrochloric acid (a.k.a., muriatic acid or acid salt) is a gas at room temperature. What you buy as a liquid is the gas dissolved in water. This is why the maximum strength available in that form is less than 40% unless it is kept it under pressure. Needless to say, it doesn't take much heat to start driving some of this gas out of solution, which is why it fumes easily. Chlorine atoms also form ferric chloride in contact with iron, the same stuff that etches circuit boards. Ferric chloride, in contact with raw iron, etches it by exchanging iron atoms. It's similar to the way rust will propagate into iron or steel to pit it, except it happens way faster. It is best to keep chlorine and its easily reactive compounds away from iron and steel if you don't want after-rust or other corrosion to occur. I've even had tools and things rust just because they were in the vicinity of a closed bottle of swimming pool grade muriatic acid. So that's just from fume exposure.

[PawB]

Check these folks out for all of your plating or stripping needs. I use their electoless nickle plating stuff and have had excellent results doing rifle bolts and other parts. They even carry nickle / boron kits, which is becoming very popular for plating AR style bolt carrier groups. They also carry a line of electroless stripping chemicals. I have used their B-9 nickle stripper on revolver parts, does a great job without attacking the base metal.
http://www.caswellplating.com/

[Bill DeShivs]

I use Caswell products (among others) and they are very good.
I use their nickel stripper as well-and it's very good.