Safe and Effective Removal Of Nickel Plating

In an article that appeared in the November 02 issue, I discussed methods that a small shop might use to remove old nickel plating from firearms.

I reviewed various methods of removing plating using chemical methods as well as by electro-chemical methods or what is termed "reverse electrolysis." Due to the limited availability of a suitable electro-chemical nickel remover when that piece was written (the product I had been using, called Super-Strip, had been discontinued), I focused mainly on a readily available chemical stripping agent sold by Brownells known as Room Temperature Electroless Nickel Strip or RTNS.

My experience at the time showed that RTNS worked well as a stripper for most newer nickel-plated firearms, especially guns that were plated by the electroless nickel process. Since that article, however, I’ve run into difficulties when attempting to strip nickel from handguns that were plated years ago using electrolytic means. On top of that, many older guns used a layer of copper plating as a base coat under the nickel.

To my dismay and contrary to some of the claims I’ve read, I found that RTNS would not It comes in a heavy-duty 10-pound pail. remove copper plating, which usually requires an electrolytic strip. In cases like this, the gunsmith is forced to locate a plating shop that offers electrolytic stripping. And in this day and age, these shops are few and far between. The conclusion I came to was that, although RTNS was good for the removal of modern electroless nickel, it won’t fill the needs of many gunsmithing shops.

Unfortunately, even after much searching, I was unable to find a good electro-chemical stripping solution that would suit the needs of the small shop. So I asked (urged) the good folks at Brownells to consider carrying Super-Strip or something like it once again, and I’m happy to report that Brownells Super-Strip is now available again.

Super-Strip is an electro-chemical or reverse-electrolysis stripping agent that will effectively strip both nickel and copper plating as well as chrome, zinc, and some other forms of plating. The components required for its use are relatively inexpensive, setup is easy, its use is uncomplicated, and the operation takes up little space. These are all qualities that make it ideal for use in a small gunsmithing shop. You should be aware that Super-Strip is intended only for stripping steel parts.

If you make the mistake of trying to strip a non-ferrous metal part, the strong electrolytic action could ruin your parts faster than you could stop the process. Let’s back up for a minute to touch on some nickel plating and stripping basics. If you’ve ever tried to blue a handgun that was formerly nickelplated, then you already know that sanding and polishing never quite removes all of the old nickel plating.

To the craftsman who doesn’t already know about this, it’s very discouraging to do a polishing job before bluing, only to find bright white spots of old nickel plating in the new bluing. Problems of a similar nature occur on guns that are replated with nickel, when spots of the old nickel are left on the steel surface. These bright spots are often not visible before plating, but show up as "bumps" (high spots) in the plating. Again, these "surprise" blemishes can be very disheartening.

The problem comes from the fact that it’s almost impossible to see the spots of old nickel on the raw steel until the finish is applied, because the bare steel and the nickel are almost identical in color. And why does nickel plating seem to "stick" to the steel so well, especially in those hard-to-reach places? To answer that question, a little background history is in order. In years past, metallic coatings such as nickel

Figure 1. Electrolytic Nickel Plating were applied using a process called "electrolytic plating." You may also have heard it called simply "electroplating." In the electroplating process, a low-voltage electric current is passed through the gun part while the part is suspended in a liquid solution called an electrolyte (see Figure 1). A metal bar of pure nickel is suspended into the electrolyte and connected by a heavy copper cable to the positive terminal of a storage battery.

This nickel bar becomes something called the "anode." The steel gun or gun part is suspended by another cable attached to the negative side of the storage battery and is placed into the electrolyte near to but not touching the anode. The part to be plated becomes the "cathode." The electric current flows from the positive side of the battery, through the anode of pure nickel, through the electrolyte, and then on through the steel gun part (the cathode).

As the current flows, nickel is released from the anode into the electrolyte and is deposited onto the surface of the gun. In similar fashion, the modern electroless nickel-plating process still makes use of a very low-voltage electric current, but rather than coming from a storage battery, this current is generated by an electro-chemical reaction as the steel part is immersed in the electrolyte. In both processes however, the end-result is a complete coating of nickel applied over the entire gun or part.

By a complete coating, I mean that every square inch of the steel gun part has a coating of nickel bonded to it. If that part was absolutely clean before the plating, the nickel would be bonded all over, even in hard-to-reach areas. Indeed, even in spots where it might be impossible to reach in order to mechanically remove the nickel. Given that information, you can see that it would be next to impossible to remove all the plating by any mechanical means such as abrasion.

There must be a better way for the gunsmith to remove every last speck of nickel, leaving the bare steel untouched. That’s where nickel "stripping" comes in, and all of these use liquid stripping solutions. One method involves soaking in a strong liquid that chemically softens the plating, causing it to expand until it floats off the steel into the solution.

The RTNS I mentioned earlier is one form of liquid stripper which is mild enough not to harm the parent steel, but it has trouble removing all of the old nickel and it won’t strip copper. Another, far more potent liquid stripper is an ammonia-based solution developed in England. This foul-smelling brew operates near the boiling point and is a vigorous stripper of nickel or copper, but it also has a tendency to heavily etch steel surfaces in the bargain.

Yet another type of liquid stripper formerly used by many tradesmen (including me) was the nitric acid-bath. Used at room temperature, this powerful acid will strip every last bit of nickel or copper. The downside is that the acid bath has the potential to be very dangerous, both for the gunsmith and for the gun he’s trying to strip. This is how the electroplating process works. The arrows describe the path taken by the electric current.

The final nickel stripping method, and the one we’ll work with here, involves the dependable and much less hazardous process of reverse-electrolysis. With this, the electrolytic or electroplating process I described above is reversed, effectively becoming an "un-plating" process. With the low-voltage electric current reversed, the nickel is actually "pushed" off the steel with the electric current flow (see Figure 2).

This reverse-electrolysis idea also uses a type of electrolyte, but this time the plated part is the anode (attached to the positive side of the storage battery), and the electric current is passed through the part. The splotchy dark areas are actually rust stains where moisture had gotten under the old plating.

The current passes through the part and through the electrolyte, and then through apiece of steel that acts as the cathode by being attached to the negative side of the storage battery. Electric current flowing through the gun causes its steel to reject or push off the nickel, which is attracted to the steel cathode and passes in suspension into the electrolyte. This is exactly the reverse of the electroplating process described above. And the product I mentioned before, Brownells Super- Strip, is the electrolyte.

This is what the Brownells catalog says about Super-Strip: "Strips plated finishes fast and easy without fumes or damage. Steel-safe, powder mixes to a potent stripping solution that quickly breaks down and removes electrolytic nickel, copper, chrome, zinc, cadmium, and electroless nickel plating with no fumes, rusting, or damage to the parent metal. Chemical activation stops after all the plating is removed. Use only on steel; other metals may be damaged or destroyed.

Requires a 6-volt, 90-110 amp, deepcycle (GC-1) battery. Here’s how Brownells Super-Strip works. When mixed with distilled water, the dry Super-Strip powder becomes a powerful liquid electrolyte. As a power source, I use a 6-volt storage battery from a golf cart that, if need be, can be hooked to a small battery charger in order to keep the battery constantly replenished during the operation. I’ve found that this heavy battery will strip several guns and their attendant parts before needing a recharge.

As for Brownells claim that Super-Strip will break down and remove electrolytic and electroless nickel, copper, chrome, zinc, or cadmium from steel without fumes, rusting, or damage to the parent metal, I’ve found that to be entirely true. The Super-Strip powder is sold in a 10pound plastic pail, which is enough to make two gallons of solution and have enough powder left over for one rejuvenation. For a strip tank, I use a small, soft-plastic wastebasket, the kind you can buy in almost any department store.

The wastebasket measures 9 by 6 by 13 inches high, and The electrostripping operation is the exact opposite of the plating process. Here the plating is actually pushed off the gun part by the action of electrical current passing through the part. will fit all but the longest barreled handguns. The photos show the stripping operation in use, tucked away in a corner of the shop.

Notice how the battery cables are attached so the gun (anode) and the piece of an old shotgun barrel (the cathode) are actually hanging into the strip solution, using pieces of flat steel strap between the cable and the pieces suspended in the liquid for strip. Before you begin, always clean the parts’and I mean clean! Thoroughly degrease and clean all parts using the exact same procedure you would use if the parts were about to be blued.

If the parts are left dirty, the stripper will eventually work through grease and oil, but it will take much longer and your strip job could turn out splotchy. Not only that, but dirty parts will prematurely contaminate your stripping solution. In practice, once you have the Super-Strip mixed in your plastic tank, hang the cathode in one corner of the tank and connect it to the negative battery cable, which at this point, should not be connected to the battery. The battery itself should be fully charged.

Never let the copper battery cable touch the liquid; always attach the cable so it bolts to steel and the steel (the cathode or a strap) is what contacts the solution. Notice that the positive cable is held to the wall with a small clamp. I did this to provide a Figure 2. Electrolytic Nickel Stripping mount for the cable, so heavier parts can be suspended from it.

Now attach one of your steel straps to the part to be stripped, then attach the other end of the steel strap to the positive cable, which is already attached to the positive terminal on the battery. Now suspend the part into the solution so it is completely submerged and at least one inch under the surface. Now that you have both the anode and the cathode suspended in the solution, take a moment to be sure that neither of these items are even close to touching the other.

If you allow that to happen, you’ll create an electrical short. And with all that backup amperage, the resulting arc will probably damage the part severely. Smaller items can be held by wrapping apiece of iron wire around them (tightly) and suspending the part from the wire into the solution, then attaching the wire to the positive cable. Larger parts with more surface area (like frame, barrel, slides, and cylinders) may take awhile to strip and will require greater amperage.

These should be bolted or securely fastened so that a solid electrical connection is maintained. In the photo, you can see one method I’ve used to suspend a handgun frame, using small bolts and nuts to clamp the steel strap to the frame in the area under the grips. The area where the bolt and strap is will not be stripped, so once the frame is

The positive battery cable (upper left side) is attached to the wall so parts can be hung from it. The long bolt can rest on the rim of the tank, acting as a hanger for the cathode. completely stripped, you’ll want to move the steel hanger to another area on the frame so the original area under the strap can be stripped. Also shown in the photos is one method for holding a revolver cylinder for stripping.

Like with the frame above, the area under the bolt heads will not strip, but after the strip is performed, the cylinder can be suspended for a few moments using iron wire attached to the positive cable until the last traces of plating are stripped. Once your part or parts are suspended in the solution, you’re ready to start the stripping operation. This is done by attaching the last cable’ the negative cable’t o the negative battery terminal.

You might want to use some sort of quick and easy attachment, such as a wing nut, on the negative terminal of the battery so it can act as your "on/off" switch. Almost immediately, you’ll notice small bubbles starting to rise above the part being stripped. This is your first indication the part is being stripped. For large parts or multiple items that will be in the tank for awhile, you’ll want to watch the temperature of the solution carefully.

I’ve found that Super- Strip operates best under 100 degrees, and once it gets up to about 120 degrees it starts to become very corrosive. I recommend using one of those inexpensive pocket-automotive thermometers to keep an eye on this. If the temperature rises to say 100 degrees, it is best to stop the connection, pull the parts and wait until the soup is back to room temperature again before proceeding.

The amount of time you leave the part(s) in the solution will vary depending on the surface area of the parts, the degree of charge and amperage capacity of the battery, ambient room temperature, and probably a hundred other variables. Most parts will strip completely within about 15 minutes, and you can stop the action by disconnecting the negative cable and pulling the part out to check. I do this about every 10 minutes to see how things are progressing.

While you have the part out to check its progress, use along wooden stick to give the liquid a stir to help keep the solution mixed. Above all, don’t forget about it and walk away from your strip operation! Yes, you can certainly do other work while you’re waiting, but it’s easy to forget you have stuff in the tank, so I suggest keeping an inexpensive kitchen timer near the strip operation.

Once you have the parts stripped or when you think they’re done, pull the part off the steel hanger, give it a fast rinse with clean water, and quickly swab some Brownells Oxpho Blue on any area that you suspect is not completely stripped. If it is truly stripped, the area will blacken at once. But if there is any trace of nickel left, the area will stay bright and you’ll know it needs more time. After the stripping is done, take the parts to your rinse tank and rinse them well.

Follow this with a hot soapy-water wash and a second rinse, and then oil the parts well to prevent rusting until you are ready to begin your prep work for later bluing or replating. To prevent evaporation of your Super-Strip solution, place a lid on your tank. I use a simple piece of 1/ 2-inch plywood cut to suit the top of the plastic tank, although plastic wrap will do the job. I’ve covered all the basic steps here, but be sure to read the instructions that come with the Super-Strip.

I think you’ll find that this is a great product that works exactly as described, but its safe use does require the operator to pay attention. I