Nickel Plating Old Radio Parts
Copyright 1997 - Robert
I thought that plating of re-plating the small parts for our restorations was just too much trouble to go thru. I had tried a few times to do some nickel plating but the part would come out with a dull finish and tended to flake off in some spots. Then because of the recession in 1975, I found myself out of a full-time job. The only job that I could find to tide me over was a part-time job at an electroplating job shop! The on-the-job experience gave me the opportunity to see what I had been doing wrong in the workshop and how to go about setting up a convenient method of plating at home.
First you will have to acquire the necessary cleaning agents, plating solution, containers and a heat source. But read on. . . . its easy and you will most likely have many of the items on hand. I’ll first present a check list of materials and then tell you how to go about getting them.
Materials for nickel electroplating:
A degreaser such as lacquer thinner ( but remember the flammability problem ! ) You still may be able to find 1-1-1 trichloroethane which will not burn or other safety solvents.
Ordinary dish washing detergent.
Dry acid ( sodium bisulfate ) This is the dry acid used to lower the pH in swimming pools and spas. Very cheap and a 5 lb. carton will last for years.
Acid base nickel plating solution.
Pure nickel plating anode.
Stainless steel ‘stripping anode’.
Copper wire ( about 22 AWG )
D. C. power source
Electric hot pot or hot plate.
400ml. Pyrex glass beaker.
D.C. ampere meter 0-2 to 0- 10 amps.
Six Ohm rheostat ( if you use a fixed voltage power supply. )
My article on the Ultrasonic Cleaning of old radio parts.
Jewelers rouge & other metal polish.
Clear brushing lacquer & lacquer thinner.
Items 1,2 & 3 of the list ( cleaning agents ) are to be used in the same manner as outlined in my article on ultrasonic cleaning. Even if you do not have an ultrasonic cleaner, you can still use the same solutions. Instead of using the power cleaning you may use a stiff, but very fine, bristle brush such are used to apply glazes to ceramic ‘green ware’. You can get various sizes at most craft shops.
Item #4 the nickel plating solution: The solution can be purchased from a hobby shop that carries plating equipment for jewelry making or you could even make your own ‘brew’. However, I think that a much better plating solution can be obtained from a local electroplating job shop. The commercial electroplater uses a solution that contains numerous additives that are just not found in hobby solutions. The most prevalent additives are organic brighteners, leveling agents and copper scavengers.
It will be necessary for you to ask the electroplater if he uses an acid base solution ( most do ) because there are alkaline base solutions which are not suitable for use at home. Also you will need to know the operating temperature of the solution. ( A typical plating temperature will be around 125 degrees F. )
These plating solutions can cost a commercial user over $20.00 per gallon but you can plate a LOT of parts with only a quart of solution. So. . . . Ask the guy for a quart and offer to pay him $10.00 - $15.00 for it.
Item #5. A pure nickel anode is required. This can be obtained from the hobby shop or you may just want to get a few slugs of electrolytic nickel from the job shop. ( I drill and tap a 6 x 32 thread hole in the center of the slug and use a stainless steel screw to attach the slug to a 3/8 inch wide strip of stainless steel that makes my electrical connection and can be bent to provide a hook to hang the electrode on the side of the plating bath. I coat the stainless steel parts with silicone rubber to keep current leakage off of the SS. ( The easiest way to get the SS sheet is to buy a pair of SS mud flaps at the auto parts store. ) Do NOT use bare copper wire to attach your nickel electrodes. The copper will ‘poison the bath’. Also don’t use 5 cent pieces as anodes because they are only a nickel alloy which is mostly copper.
Item #6. Stainless steel ‘Stripping anode’. This can come from the hobby shop or you can use a strip of the SS mud flap mentioned above.
Item #7. Will be used to suspend the parts to be plated.
Item #8. D.C. power source. . . . You will need a D.C. source that can deliver up to 4.5 Volts at a current of 1.5 Amps. If you do not plan to do more than a few hours of plating then three alkaline ‘D’ cells may do the job for you. I have found that you can pick up used 5 Volt DC supplies at hamfest fleamarkets for less than $5.00 that will deliver six or more amps. For lower voltage, just run the power supply from a VARIAC or use a 25 Ohm rheostat in series with your plating anode rated for high current. Its always good to monitor the supply current to let you know if the plating current gets too high.
Item #9. Electric hot pot or hot plate. You will have to keep the plating solution heated above the typical working temperature ( about 125 degrees F. ) The easiest way to do this is to place a beaker full of plating solution in a hot water bath. I have found one of these small electric hot pots to be ideal for this purpose. They are designed to heat a can of soup or boil water for two cups of coffee. I regulate the pot temperature by powering the hot pot with a lamp dimmer control or Variac.
Item #10. 400 ml. Pyrex glass beaker. You could just use any type of glass container such as a wide mouth peanut butter jar but glass beakers cost less than $3.50 and are available from science hobby shops and medical supply houses.
Item #11. DC ampere meter. The meter is required so that you can know the plating current being drawn. The plating rate is directly related to the current density expressed in amperes/sq. ft. of plating surface.
Item # 14. The jewelers rouge & other polishing materials can come from a hobby shop or an auto restoration supply house such as Eastwood’s.
Preparing the part for plating:
Follow the cleaning procedures given in my article on ultrasonic cleaning. With a clean part, you can now inspect it to see if there are any flaws which need to be filled with Stay Brite solder or polished out. An item to be plated can never receive a bright mirror finish unless the item is polished before plating. Remember that most good electroplate is only 0.0003 to 0.0005 inches thick! In most cases the flaws can be removed with just jewelers rouge or a very fine wire wheel. A ‘Moto Tool’ is very handy for this task.
After polishing the part, attach a bare copper wire to the part. For very small parts such as nuts & screws it is adequate to suspend the part thru the hole in the nut or hold a screw by looping the wire around the threads. On larger parts such as a tube socket shell or rheostat base you can experience uneven plating if it is suspended from just one point. In order to make the current density more even on the part simply suspend it from two or more points.
The item to be plated must be absolutely clean. You are using an electro-chemical process. Materials such as dirt and oils WILL interfere with the process ! So; repeat the cleaning procedures in the degreaser, detergent and acid making sure to handle the parts by the hanger wires only!
As a final step before plating it is a good idea to re-activate if there is old nickel plate on the part. ( If you do this, do not hang the part by bare copper wires because the copper will poison the plating bath. --- Use tinned wire or stainless steel wire. ) This is done by connecting the negative side of the power supply to the stainless steel electrode and connecting the parts to be plated to the positive side of the power supply. Turn ON power and increase the current until there is a free flow of gas bubbles from the parts. A minute or two of ‘reverse plating’ is usually adequate. Longer re-activation will begin to dull the finish to some degree.
Plating the part:
Make sure the nickel plating solution is up to temperature then place the part in the solution. The plating bath temperature is not critical. It is only important to make sure that you are above the recommended operating temperature. Low temperatures promote blistering and dull plating. ( For example the solution that I use normally operates at about 125 degrees F. so I make sure that the plating bath is up to 140 degrees F or so before I start to plate. )
Make sure that you have reversed the connections to the power supply so that the part to be plated is now connected to the negative side of the supply and the positive side is now connected to your pure nickel anode. Allow a few seconds for the part to heat up to the temperature of the solution before turning on power. The plating solution must be under constant agitation while plating in progress. The easiest way to do this is to stir the solution with the part being plated. Also rotate the part for more even plating.
The current you should use has to be little more than an educated guess. It is important to remember that too high a plating current will result in blistering or a build up of rough nickel on the edges of the part. Too low a current density will result in poor ‘throwing’ of the plate into the recesses of the part. I can however, give you a few examples:
With a plating temperature of about 125 degrees F. , I can plate about ten 6x32x ˝ inch machine screws with a current of about ˝ Amp. in about ten minutes.
The shell of a Federal UV type tube socket plates nicely at about 1 ˝ Amps. in about 15 minutes.
The time necessary to build up sufficient plate will vary with the solution used, the operating temperature and the current density used. In general most parts will acquire enough plate in 10 to 15 minutes. You can tell when you have enough plate simply by checking the part for only a second or two every few minutes. You should expect for the part to take on a dull nickel finish for a few minutes. Then the plate will slowly begin to become bright and mirror like. The mirror like areas will be spotty at first but will grow and finally merge together if the part was well polished. As soon as the part is as mirror like as you think it will become; take it out! If you continue to add plate, the finish will begin to get rough along the edges and at the point where the part is suspended.
Now rinse and dry the part completely. If any dull areas remain, but you are sure there is good plate, then you might try to polish out these areas with jewelers rouge and a piece of felt. Do this lightly by hand!
After you polish the part, clean it in the degreaser and get the part absolutely dry with a heat gun. If the part is steel, it is a good idea to give it a thin coat of brushing lacquer. In even the best nickel plate, there will be microscopic pitting of the plate that will leave minute areas of the base metal exposed to the air. Rusting will start and the iron oxide crystals will push up and fracture the nickel plate. The lacquer coat will seal these pits and retard the corrosion/rusting process for many years.
Give nickel plating a try. . . . . Copyright 1997 - Robert Lozier, Monroe, NC; USA
Note: Make sure, if you are re-plating, that the part has just nickel plate on it and not silver or chrome plating. I have noticed that some of the RCA tube socket shells are chrome over nickel plate. Some Kennedy dials are silver plated while others are nickel plated. And of course the Aeriola Sr. And Jr. Dials are silverplated.
Questions about this article? Contact Robet Lozier KD4HSH@juno.com
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