Introduction

Copper electroforming is a powerful technique used to form copper shells over matrices that are subsequently either burned or melted away, leaving only the copper shells behind. This is accomplished through the electrodeposition of positive copper ions over a negatively-charged matrix through an electrolytic copper salt solution.

Warning

Electroforming, when all necessary safety procedures are followed, is a safe, stable process. Because the electrolytic solution is primarily composed of copper sulfate and sulfuric acid, proper gloves and eye-wear is a must, as is proper ventilation. And because electroforming utilizes electrical current, a full knowledge of safe electrical workplace practices is necessary. Please carefully read the safety precautions for all the chemical materials you purchase, as well as all safety precautions for the rectifier. Also, research the risks associated with all component chemicals before you proceed. Cornell University's toxicity report is a good place to start for copper sulfate, and Iowa State University's Material Safety Data Sheet, for sulfuric acid.

No art project is worth damaging your health. Please proceed in a thoughtful, well-informed, and safe way.

Tools & Equipment

• Rectifier. A 5 amp rectifier is sufficient for solutions up to 2 liters, and is a good place to start. Rectifiers of 25 amps or more are necessary for larger volumes.

• Glass receptacle. This can be a standard Pyrex beaker, or flea market find.

• Copper wire. I use 16ga or larger, but others seem to prefer smaller gauges (with higher gauge numbers). Often, it depends upon the size of the object you are electroforming.

• 2 small, cheap watercolor brushes. 

• Either a hunk of clay to stick drying objects into, or something to suspend them from.

• Pliers, possibly tweezers--the cheaper ones, as the electrolytic solution causes iron to rust on contact.

• latex/ rubber gloves, and eye-protection. Face-shield not a bad idea.

• A small, cheap, fine brass brush; or a Dremel with a fine brush or wheel.

Materials

• Lacquer. Some artists find success with water-thinned white glue like Elmer's, which is cheap and easy to find. I prefer Chinese red lacquer--it's pricey, but is a strong acid resist that allows for the preservation of the most minute details. Beyond that, its deep vibrant carnelian red is a joy to work with.

• Conductive Paint. Be aware that no matter where you look, it's going to be pricey. I use two different kinds:

  • Midas Copper Conductive Paint, sold by Rio Grande. This works very well, as copper is a conductor, but the paint itself cannot be thinned once it starts to thicken, and sometimes the nano-particles of copper can form chunks that are difficult to work with. In summary, this paint works well until it doesn't, and occasionally, it can fail entirely.

  • Graphite Conductive Paint, sold by Sherri Haab. This paint works a little less well generally, as graphite is a semi-conductor (not a conductor like copper), and can sometimes produce uneven results. The copper ions are attracted to the graphite and form a copper layer over it, but because the newly-plated copper is more conductive than the graphite, the new plating can sometimes occur over the new copper plate and not the yet-to-be-plated graphite. I get around this by 1) attaching the cathode to different places on the object, and 2) not submerging the cathode in the solution if possible. One upside to the graphite: unlike the copper paint, it has yet to entirely fail.

  • As an aside, I've tried making my own copper paint by precipitating copper metal from ascorbic acid and copper sulfate and suspending it in an acrylic medium, but my results have been mixed (at best).

• Electroforming Solution. If you are starting out, I'd highly recommend Midas Bright Copper Electroforming Solution, and in any case, if you're keeping to one or two liters, it's cost effective to purchase the pre-mixed solution. Anything larger and you should consider mixing your own solution (see Electroforming Solution Recipes for details).

• Brightener. As far as I'm aware, the only possibility here is Midas Replenishing Brightener. 

• Copper Anode. Any hunk, or sheet, or cable, or plate of pure copper will do--it just has to be proportionally large enough to resupply the electrolytic solution with positive copper ions as ions are deposited upon the matrix. For this work, it's not necessary to buy perfect pieces of copper--any malformed, dented, torn, scratched piece will do. My very best advice: do everything you can to find a friendly scrap yard in your area that will let you buy their copper. It's getting hard to find friendly scrap yards anymore, but if you can find one, it will save you an arm and a leg.

• Baking Soda and paper towels. For spills.

Important notes

• Use correct amperage. Check bath after thirty minutes or so--the copper should be "penny bright." If it salmon-pink, the amperage is too low; if it is dark brown, the amps are too high. Amperage should be set at 1/10 for every square inch.

• Add one drop of brightener for every 15 amp hours.