Chemical Engineering Interview Question:

We wanted to know how to impart various colors to copper wire by simply dipping them into various chemicals, formulations, etc. This copper wire is to be used by us for our hobby of making various art objects from copper wire.

Submitted by: Administrator

Changing the color of copper by means of chemical reactions is a dangerous Endeavour that I really do not recommend. However, there is something you can do to get a green color, if fact if you are familiar with the Statue of Liberty here in America, this would explain why it is green. You see, the outside of the statue is coated with copper and being in New York City, it is subjected to acid rain. This causes the formation of another chemical that coats the copper and gives the statue its green color. The two acids that you can use are nitric acid (which works best) or sulfuric acid (which will probably require some gentle heating along with the acid). I am not sure if there were a good way to get nitric acid out of something you may have around the house, you would probably have to buy it.

Sulfuric acid can be obtained from car batteries (the liquid inside). You will want to boil the mixture (to concentrate it by evaporating the water), until you see white fumes (which are very dangerous). Then put your copper is while the acid is hot and leave it there until you get the color you would like. If you are going to do this, please do it outside or in a well ventilated area and make sure you have some baking soda handy is case you get some of the acid on your skin. If you are looking for a different color or more colors...
Submitted by: Administrator

We suggest contacting someone who manufactures copper or someone who specializes in it. Please be very careful if you do any of the experiments that we have suggested. The green color that you get will not be an artistic bright green, but an unattractive dark, milky green. You may have to consider making your art out of something that is a bit easier to color. Good luck with your project!
Submitted by: Administrator