Have you ever tried to plate copper? It’s much less expensive than gold or silver, yet incredibly beautiful. Use simple redox chemistry to make a keepsake copper ornament. Can you think of a better way to remember how much fun you had in chemistry class?
Copper Plated Ornament Materials
The key materials for the project are a metal ornament and copper(II) nitrate solution. The basis for the electroplating process is the metal reactivity series, so select a metal higher than copper on the list. Zinc or galvanized metal works best.
- Metal for the ornament
- Masking tape
- Copper(II) nitrate solution [Cu(NO3)2, ~0.1 M]
- Utility knife
- Steel wool
- Tin snips (optional)
Good metal choices include galvanized sheet metal, galvanized wire, or hardware cloth. You’ll find these metals at a hardware store, like Lowe’s or Home Depot.
How to Copper Plate the Ornament
- If desired, cut or form your metal into a snowflake or star or other holiday shape. You can wrap wire around a sphere to make a glittering ball or bend it to conform to a traced shape (like a star or angel).
- Once you have a shape you like, use sandpaper or steel wool to smooth any rough edges. Tin snips are nice to use with hardware cloth.
- If you want part of the ornament silver (zinc-colored) and part copper, cover all areas you want to remain silver with masking tape.
- You can use a utility knife to etch a design into the masking tape or can scratch the tape away with an awl or any sharpened object. This is nice if you have a rigid piece of metal and simply want to decorate it with a shiny copper design.
- Dip the ornament in the copper nitrate solution until the uncovered areas are coated with the metal. Alternatively, you can use a cotton swab dipped in the solution to paint a design onto the metal.
- Rinse your ornament with water, remove any masking tape, and allow your decoration to dry.
How It Works
Copper replaces zinc from galvanized metal via a single replacement reaction.
Zn(s) + Cu(NO3)2 (aq) → Cu(s) + Zn(NO3)2 (aq)
Galvanization is coating a metal with a layer of zinc. Masking tape protects covered metal from reacting, so the galvanized metal of the untreated sections remains shiny. Copper is low on the metal reactivity series, so you can use this reaction to plate most metals. It does not work with silver, gold, or platinum (not that you’d want to cover them up with copper anyway).
Tips & Ideas
- If the metal is dirty or you wish to remove its coating, you can dip it in dilute hydrochloric acid (HCl, also called muriatic acid) until the bubbling stops, rinse with water, then treat with the copper nitrate solution.
- A related version of the project uses pennies, lemon juice, and an iron or zinc ornament. The lemon juice is a weak acid and an electrolyte. Pennies have a copper coating that dissolves in the lemon juice and plates the other metal.
- If you don’t have copper(II) nitrate, substitute copper(II) sulfate (CuSO4).
- Dufour, Jim (2006). An Introduction to Metallurgy (5th ed.). Cameron.
- Stelter, M.; Bombach, H. (2004). “Process Optimization in Copper Electrorefining”. Advanced Engineering Materials. 6 (7): 558. doi:10.1002/adem.200400403
- Todd, Robert H.; Allen, Dell K.; Alting, Leo (1994). “Surface Coating”. Manufacturing Processes Reference Guide. Industrial Press. ISBN 0-8311-3049-0.