General Plating Procedure Instructions for Nickel, Gold, Silver, and Rhodium

For Nickel, Gold, Silver, and Rhodium

Contents

1. Preparation

1. Articles which are to be plated must be cleaned thoroughly after polishing to remove all possible contaminants. Ultrasonic cleaning with a solution of water, liquid soap and ammonia is best. If ultrasonics are not available, then boil your pieces in the same mixture of cleaning solution for about 30 minutes.

2. After cleaning, the articles should be rinsed in running water to remove all traces of the previous soapy solution. If you are not certain that the jewelry is absolutely clean, you should give it the "water-break" test.

In this test, water is run over the surface of the article. If it forms a smooth, continuous, unbroken film coating the entire surface, this indicates that all greasy substances have been removed. If, on the other hand, the film of water is broken into separate streams or droplets, then the article has not been sufficiently cleaned and should be returned to the soap-water-ammonia cleaning bath.

2.Electrocleaning

Electrocleaning is a procedure that results in an exceptionally clean piece of jewelry. This step is absolutely necessary when plating with rhodium but not required for other plating solution.

1. Clip the black negative wire to the jewelry (or jewelry rack) and the red positive wire to your stainless steel anode. The electrical set up for Electrocleaning is exactly the same as plating.

2. Heat the Electrocleaning solution to around 190º F and maintain that temperature.

3. Set the voltage. Voltage is typically set a 10 volts, but some operators prefer a voltage as low as 6 volts and some prefer a voltage as high as 15 volts.

4. Immerse your jewelry in the electrocleaner solution for 30 seconds, no longer Excessively-long immersion will darken the metal.

5. Unclip the rack.

6. Dip the rack with the jewelry into the running-water rinse-tank to rinse off the electrocleaner from the rack and from the jewelry.

3. Nickel Plating

1. Set the rectifier at 1-1/2 to 2 volts with the solution between 120º F and 140º F (consult your plating solution label for temperature requirements).

2. Clip the negative (-) black wire to the plating rack.

3. Immerse the rack in the nickel plating solution for several minutes. Experiment with various lengths of time from 3 minutes to 10 minutes to determine that time which is best for you.

4. Agitate the nickel plating solution.

5. Unclip the rack.

6. Rinse the nickel plating solution from the rack with the jewelry in the running water rinse-tank.

3.1. Maintenance of Acid-Based Nickel Solutions

• Acid based nickel plating solutions which do not work properly after some time can be tested only by experienced platers and then corrected.

• For small volume plating shops the most practical method is as follows:

  1. Test with the "pH" papers. If the "pH" is below 3, then add 1 cc. of chemically pure sulfuric acid to bring the "pH" up to 3.

  2. Stir the nickel solution.

  3. Wait 5 minutes.

  4. Test the "pH". If it is still below 3, add 1 c.c. of sulfuric acid.

• The other correction you can make is to add 10 cc. nickel brightener and stir. If plating is not improved, then add another 10 c.c. of nickel brightener and stir. If the problem is still not solved, then discard the nickel plating solution and use a fresh nickel plating.

4. Gold Plating

1. Set the voltage of the rectifier at 3 to 4 volts with the solution at 100º F. Consult your plating solution label for temperature requirements.

2. Clip the negative (-) black wire to the plating rack.

3. Immerse the rack for 30 seconds to 1 minute.

4. Moderately agitate the gold plating solution.

5. Unclip the rack.

6. Dip the rack with the jewelry into the gold-dragout glass jar. The liquid gold solution which clings to the rack and to the jewelry will come off into this jar and not be lost.

7. Dip the rack with jewelry into the running-water rinse-tank.

4.1. Gold Plating Notes

• For a thin coating of gold plating (flash plating), use Shor standard gold plating solution.

• For a heavy coating of gold plating, use Shor Heavy gold plating solution with titanium anodes instead of stainless anodes and have the solution at 80º F to 100º F with 1-1/2 to 2 volts.

 

5. Rhodium Plating

• Set the voltage at 6 volts with the rhodium plating solution at room temperature.

• Clip the negative (-) black wire to the plating rack.

• Immerse the rack in the rhodium plating bath for 30 seconds to 1 minute.

• Unclip the rack.

• Dip the rack with the jewelry into the rhodium dragout glass jar. The liquid rhodium which clings to the rack and to the jewelry will come off in this jar and not be lost.

• The "force" with which the rhodium is thrown at the article is determined by three factors:

  1. The voltage
  2. The temperature
  3. The relative size of the anode to the work

  The higher the voltage, the higher the temperature, and the larger the anode with relation to the work, the greater is this force. These three factors must be kept within near-perfect balance so that the force will not be too great or too small. Too great or too small a force will result in an unsatisfactory plate.

  It should be clear that the temperature can be increased simultaneous with a voltage decrease (or vice versa) without changing the force. There is, therefore, a wide range of conditions under which rhodium can be successfully plated. For example: plating can be done at room temperature (approximately 70º F) at 6 volts; or at 100º F at 2 volts.

• Using platinum anodes or platinized titanium anodes and with the electric current turned on, the plating rack with jewelry is immersed in the rhodium plating solution.

• Take it out every few seconds for inspection. With each immersion, the brightness of the plate will increase until a maximum brightness has been reached.

• Once that optimum plating brightness is reached, there will be rapid darkening with each additional immersion. The optimum plating time must be determined by experience. Excessive force, resulting from a combination of excessive temperature and/or voltage and/or anode size, results in a dull plate. When the article is kept too close to the anode a brown "burn" mark results.

5.1. Maintenance of Rhodium Solutions

• About once a week (depending on how much rhodium plating you have done) pour the solution through filter paper to clean it of contaminants. Some contaminants will be dissolved in rhodium and cannot be stopped by filter paper. If this happens, put activated charcoal in your filter paper before pouring the rhodium solution through it. The activated charcoal will absorb the impurities. Since it will also absorb some of the rhodium, use the activated charcoal only when necessary.

• Pour some of the rhodium solution from the normal rhodium plating solution which is in the glass plating jar into a small glass bottle (about 1 ounce of solution). Place this small bottle in a drawer so that it is not faded by sunlight. After a few days of rhodium plating, compare the color of the rhodium solution in the glass plating jar with the color of your small sample. If the color of the rhodium plating solution is noticeably lighter, then add rhodium replenisher to your rhodium plating solution until the rhodium plating solution is as dark as your sample.

6. Silver Plating

1. Do not plate at a temperature above 65º - 75º F.

2. Set your voltage to zero.

3. Immerse your rack into the solution.

4. If plating small jewelry (such as small earrings) increase the voltage to 1-1/2 volts. If plating larger pieces, increase the voltage to 2 volts.

5. Plate for about 15 seconds, agitating the rack in the solution.

6. Visually inspect the plating.

   1. If the desired plating has been achieved, go to step 7.

   2. If the desired plating has not yet been achieved, immerse for another 15 seconds.

   It is rare that more than 60 seconds of total immersion time is required to achieve the desired plating effect.

7. Immerse one last time for 15 seconds.

8. Dip the rack with jewelry into the rhodium-dragout glass jar to remove and recover rhodium. When the rhodium-dragout glass jar contains enough rhodium plating

solution, it may be poured into the regular rhodium plating solution to replenish it. The same is true for the gold-dragout jar replenishing the gold-plating solution.

9. Dip the rack with the jewelry in the running-water rinse-tank.

10. Dry the jewelry. Using coated steaming-tweezers, hold each piece of jewelry, one at a time, under a blast from the steam machine. This will dry the jewelry, avoiding water stains. It will also give the jewelry a high shine.

 

6.1. Silver Plating Notes

• Many solutions come in concentrated form, requiring that you add water.

• Electrocleaner comes in powder form, requiring that you add water.

• The water for all solutions must always be distilled water.

• One pound of Shor electrocleaner powder makes 4 gallons of electrocleaner solution.

• There is no test to determine when to discard the electrocleaner solution. Very busy factories discard the solution every day. Less busy factories discard the solution every week. Those with little plating activity discard the solution every month.