Studio Notes: Electroforming Is Electrifying
Electroforming is a great way to encrust jewelry projects with layers of flowing copper. But what are the proper voltage and amp settings on a Caswell rectifier to create a plated surface on a piece of jewelry? The Caswell is one of many power supply devices intended more as laboratory test equipment for engineers. It is also known as a rectifier. They have been adopted by etching and electroforming jewelers, and the Caswell was featured in Denise Peck’s video Easy Electroforming for Jewelry.
Above: Briana Swisher of Earth and Metal Shop used electroforming to create this open back, double-terminated Tibetan quartz ring encased in textured copper with an oxidized finish. Photo by artist.
For her demonstration, though, Peck used a pocket-sized micro-processor developed by electrical engineer Dan Haab for his wife, Sherri Haab. Sherri is the author of 30 books on jewelry techniques. Compared to a lab-style power supply, their device is programmed to make calculations automatically. Flip the switch, change your set up, and you can electrically etch jewelry designs on sheet metal, too.
So, when looking at all of the dials and buttons on a desk top power supply, to what settings should you turn the volt and amperage dials for electroforming?
The short answers:
- Asterion provides a calculator, which is supposed to take care of a lot of this guess work. Check out the free app.
- Sherri Haab recommended this site as a great place to get your questions answered. It’s where I found the app suggestion above.
The longer answer? Here is Sherri’s take:
“Electroforming can be very complicated,” Sherri says. “There are many variables, including the size and shape of the piece you are forming, the composition of the object, the chemistry of your solution (acid balance, brightener, etc.), and your set up, let alone knowing your equipment. Here are a few general guidelines to help you get started.
“First, keep in mind that electroforming is all about CURRENT. The basic rule of thumb is that you want to deliver 100mA of current per square inch of surface area. So if we use a plastic toy figure for example, and it has a surface area of 2 square inches, you’ll want to aim for 200mA or 0.200 (as read on your rectifier).
“After preparing and attaching a wire to your object (toy) for electroforming, attach your clips to the anode and your piece. Turn the voltage up to 2V, which is more than enough for copper electroforming. Make sure your constant current is set.
“Submerge the piece in the solution and adjust your current. Start at zero with your amps and turn up to 200mA (0.200) to accommodate the size of the object. Remember that you can adjust the current higher or lower as needed. Low and slow is always better for a smoother plate. Learning where to set and adjust the current takes experience and there is a learning curve. Too much current or too little current will change the texture and surface of the copper. After awhile, it becomes intuitive.
“Without an understanding of electro-chemistry, people get confused,” Sherri says. “That is why Dan decided to create a machine that would be specifically for electroforming jewelry. Our controller allows the user to select a current without having to manually achieve a desired current.”
Betsy Lehndorff has been writing for Lapidary Journal Jewelry Artist since 2010. She will be writing about her experience in Kate Wolf’s class in 2018, along with her grant-writing adventures as a silversmith. You can reach her at firstname.lastname@example.org.
Learn more about electroforming and other fun metalsmithing techniques!