How do you electroplate flowers, leaves, animal skulls, and other organic materials?
This was the very first question asked when www.finishing.com went on line in 1995, and has been asked again and again as the years go by.
You may want to consult the chapter "Metallizing Nonconductors" in the Metal Finishing Guidebook.
There are five metallization processes that I am know of; you will choose one depending on the nature of the substrate and the end use of the item:
- Probably the easiest to understand approach is to simply paint the items with a paint that contains metal particles or flakes, usually copper, silver or zinc. This is used on, for example, surface-mount electronic components to make them plateable and ultimately solderable.
- You can apply a spray of colloidal conductive material, either carbon or metal. Actually, this is not very different than the first approach except that the particles are extremely fine, and the process is designed specifically for the purpose of allowing fine decorative plating onto non-conductors.
- I'm not really familiar with it, but there are the solutions designed for brushing onto ceramics and then firing in an oven. The familiar gold edging you would see on fine china is an example. One supplier is Hawking International Ltd, The Stenders, Mitcheldean, Glos, UK; they call their product "Liquid Bright Gold".
- Two-part silvering solutions are used for many different applications including plating of lacquer masters for vinyl records. You simultaneously spray a soluble silver salt and a reducing agent in order to reduce silver metal onto the item in question. This is essentially the same method (Brashear process) used to make mirrors.
- The fifth and most complex method is the one usually done for plating on plastics: after you etch the material to give it some tooth, you dip it into stannous chloride or palladium chloride, or both in sequence, and then use the conductive seeds that you have thus formed as the nucleating points for electroless copper or electroless nickel deposition. This is usually a high volume industrial process and invariably relies on proprietary chemistries available from the major suppliers like Technic and Macdermid, and offers the advantage of a truly robust process for difficult environments like automotive exterior brightwork.
It is important to remember that metallization is a carefully honed art, and if you are trying to plate flowers or leaves and so on, you certainly should not expect to get the same kind of results in early trials as are achieved by artisans who have been working for decades to perfect their trade. You also need to realize that plating chemicals are aggressive, and you will probably have to develop some techniques with wax or lacquers to keep the plating chemicals from attacking the organic materials. If the item is important to you, don't take a chance trying to plate it until you are really good. And, of course, consult EPA and DOD regulations.
See the cover story of Plating & Surface Finishing, Dec. 1996, "Preserving Nature At Enchanted Gold--An Art & a Commitment" -- it doesn't tell you how to do it, but the photos of their work are certainly an inspiration! You will also see such items for sale on the web; try the keywords "gold plated orchids" in the search engines.