Here, I hope to present a very simple description of the process of electroforming. In his book, Jewelry: Concepts and Technology (New York, NY: 1982, Doubleday), Oppi Untract defines electroforming as the "process of synthesizing a metal object by controlling the electrodeposition of metal passing through an electrolytic solution onto a metal or metallized form." Very simply, a metal skin can be built up on a metal surface, or any surface that has been rendered electroconductive through the application of a paint that contains metal particles. This differs from electroplating basically because the skin is much thicker and can exist as a self-supporting structure if the original matrix is removed. I will discuss electroforming on glass beads here, but the concept is the same whether the object being electroformed is glass, wax, or really anything that can stand up to the acid in the electrolytic solution. The object being electroformed can be a permanent part of the end product or can be temporary (as in the case of wax), and removed later, leaving only the metal form, the "electroform".
The easiest (and safest) metal to electroform onto a surface is copper, which can be plated later in gold or electroformed in silver. Both the silver and gold processes involve cyanide baths, so I haven't been eager to try them!
To electroform a metal surface onto a glass bead, you will need the following: a rectifier (either a 3 or 10 amp is fine), a clamp and lead set, a spool of 18 gauge copper wire, two 1" x 1 1/2" pieces of 20 gauge copper sheet, a 1000 ml Pyrex beaker (or a plastic food storage container of the same size), one quart of electroforming copper solution, and 2 ft. of very thick copper wire (about 8 gauge at least - the bigger the better). These all can be found in Rio Grande's tool and equipment catalogue (www.riogrande.com). The best source I've found for electroconductive copper paint, which you will apply to the surface of the bead where you want to electroform, is Safer Solutions of Philadelphia, PA, (215)232-5459.
The basic concept involved in electroforming is relatively simple: The rectifier supplies both positive and negative charges; positive to the anodes (the copper plates) and negative to the cathode (the bead painted with the electroconductive paint). The anodes (I use two), and the cathode are suspended into the beaker containing the electroforming solution by 18 gauge copper wires which are attached to 8 gauge copper rods placed over the Pyrex beaker. The positive and negative lead wires coming from the rectifier are clamped to the ends of the 8 gauge copper rods. During electroforming, the negative charge carried to the bead causes it to "attract" copper ions from the solution. These deposit on the surface of the bead where you have painted it, while copper ions from the positively charged anodes leave the anodes' surfaces and replenish the bath.
To prepare your bead to be electroformed, make sure it is well cleaned. Paint the electroconductive paint where you want the copper skin to grow. The copper skin won't permanently adhere to glass so make sure that the paint is applied as a shape that won't peel or slide off of the bead. In other words, make sure that it will be firmly anchored as a result of the shape it takes. Electroforming a ring around a spherical bead won't work, nor will electroforming the tip of a cone shape. The resulting copper skin could come right off. Electroformed copper around two-thirds of a bicone will remain permanent as will a sheath that goes around an urn shape and through its handles.
Allow the electroconductive paint to dry for 1-2 hours. I just stand the bead, which has been stuck on a wooden toothpick, into a Styrofoam meat tray. Do not handle the painted portion of the bead - oil from your fingers may hinder the electrodeposition. The drying process can be sped up through the use of a light directed at the bead or a hairdryer.
To prepare your anodes, take your small rectangles of copper and drill a hole in one of the 1" ends (this is where the 18 gauge wire will attach to suspend it into the bath). Make sure that the anodes are clean. You can use a Scotch Brite pad to clean the surfaces.
Cut an 8" piece of copper wire off of the 24" of 8 gauge wire you have. This will be placed over the center of the Pyrex beaker. The remaining 16" should be bent into a "U" shape and placed to surround the 8" piece, without them touching. Fill the beaker with electroforming solution to within about 2" of the top.
Cut two pieces of 18 gauge copper wire long enough to suspend the two copper rectangles in the solution but short enough so that the drilled holes and suspending wire are not submerged. Wrap the other end of each 18 gauge wire around the middle of the outside rods of the "U" shaped wire.
Your bead, the cathode, is suspended in the bath by another piece of 18 gauge wire. The wire should go through the hole in the bead, and be bent in such a way that it comes in contact with the paint on the bead. The other end of this wire attaches to the center rod of 8 gauge wire suspended on the beaker. This wire is conducting the negative charge to the bead which will cause the electrodeposition of copper ions on its surface. Be careful that the top hole of the bead, where the wire is entering, isn't submerged into the bath. You don't want the wire to have electrodeposition as it both enters and exits the bead or it will be difficult to remove (This is assuming that the bead whole is relatively small. If it is 3/32 or larger, this is not a concern). The bead should be hanging in the center of the beaker, with an anode on either side of it. Try to space the anodes at an equal distance from the bead (the cathode). They should also be roughly twice the surface area of the cathode.
You are now ready to turn on your rectifier and begin electroforming! Be sure that the 8 gauge wires over the beaker do not touch. Positive and negative contacts may blow out the fuse in the rectifier (if your model has one). Turn the knob to see if the needles indicating voltage and amperage move. If they do, you have set up a system that delivers a charge and completes a circuit. If the needles do not move, here are some items to check:
1) Make sure that the alligator clips at the ends of the lead wires (which are clipped to the 8 gauge wire rods over the beakers) are clean and rust free. If they look old and dirty, you can use a household file to clean them up;
2) Make sure that your 8 gauge wire rods are free of copper salts - a quick cleaning with a Scotch Brite will help here;
3) Make sure your rectifier is plugged in and turned on!
A slow deposition of copper using low amperage is preferable over a rapid buildup, which will frequently crumble off. I use about .3 volts and .1 amps (which you control with the knob on the rectifier) when I begin to electroform, and the process can take around 18 hours or more for one bead depending on the thickness desired, the area covered, etc.
During the electroforming process, change the point of contact between your bead and the wire that is conducting the charge to the painted surface, several times. If you leave the wire in one spot during the entire procedure, that spot will not be covered with copper. I wait until the copper skin has begun to grow consistently over the bead, and no paint is showing. Then I remove the bead from the bath, carefully rinse and dry it, and paint electroconductive paint over the place where the wire had made contact. When it is dry, I reposition the wire to touch another spot that has already begun to electroform and return the bead to the solution.
Periodically during the electroforming, it is a good idea to clean your anodes. When you remove them from the bath you may notice that a residue has darkened the copper. This is cupric oxide. You may also notice a buildup of copper salts. These can be removed with a Scotch Brite pad. Make sure you dry your anodes of any tap water before returning them to the solution so you don't contaminate the solution with metals that might be in your water.
When your bead is electroforming, you will find that the copper skin is rather baroque and can be granular, compared to the thinner coatings achieved through electroplating. In addition, you may see that the skin has built up unevenly over the surface. Because projections of any kind are places of high current density, there will be more electrodeposition at peaks, ridges and squared edges than there will be on round edges or flat surfaces. This can serve to define the shape of the bead and create textural interest.
If the copper buildup seems dark and not as dense as you would like it, you can add a few drops of brightener, available from the same place as you get your solution. This will encourage the ions to deposit more densely on the surface of the bead and will contribute to a shinier appearance.
When you are satisfied that your bead is electroformed as heavily as you want it, remove it from the bath and rinse it. The color will be a matte pink. To bring out a bright copper shine, scrub it gently with a brass brush lubricated with liquid detergent. Electroformed copper oxidizes quickly when left in the air. You will need to seal the surface with lacquer to prevent this. You may prefer to patina the copper with one of the solutions available through jewelry supply houses, such as liver of sulfur. Ammonia will impart a nice green patina to a copper surface.
The electroforming solution can be reused, as can the anodes. Make sure you filter the electroforming solution through two coffee filters dampened with distilled water before returning it to its original container. Adding rinsed charcoal (like the kind you would use for a fish filter) to the coffee filters, will help to remove any organic contaminants that may have gotten into the solution.
I hope this description of the electroforming process is clear and understandable. Please read and familiarize yourself with all the warnings printed on the materials you will use - your health is YOUR responsibility! Eye protection, a fume mask and rubber gloves are in order when working with acids. And if you aren't wearing old clothes to begin with, they'll be old soon enough!
There is a helpful section in Jim Kervin's recent booklet about me that pictures the electroforming process with the full setup.
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Tool Kit for Electroforming
3-10 amp digital rectifier (with clamp and lead set)
1000ml Pyrex glass beaker or similar nonmetallic container
copper anodes (two 1" x 1 1/2" pieces of 20-24 gauge copper sheet)
24" 8-gauge (or larger) copper wire
spool of 18-gauge copper wire
1 quart electroforming copper solution
electroconductive copper paint
replenishing brightener for the electroforming solution
coffee or charcoal filters
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tips archive - representational beads
With thanks to Hoover&Strong and Lapidary Journal magazine for the illustrations for this article.