Patina is "a thin layer that forms on the surface of stone; copper, bronze and similar metals (tarnish produced by oxidation or other chemical processes)". It is also a great technique to give pennies a pretty colour!!
Looking on Pinterest, it seems like there are various ways of achieving a patina finish. I used the vinegar and salt method, taken from this great tutorial by Rena Klingenberg.
To start, I raided the coin jar for about 40 pennies.
I was thinking of decorating a plant pot with them, but I guess they may need to be 'sealed' first. Or perhaps mount them and display in a frame? What do you reckon?!
Update: 10th July 14 - this post has been featured here by Craftgawker