Open your can of cola and pour the contents into a cup, put it to one side we'll be using it in awhile. Now using a can opener cut off the top of the can, put the top to one side. I'll show you a use for that in another article. Now clean and dry the inside of the can.
The inside of the can has a protective plastic coating that we need to remove, so use your wire wool and get scrubbing. I found a way to speed this process up was to use a drill. Stuff a load of wire wool into the can and use a spade bit to rapidly turn it. Be careful not to apply too much pressure as you don't want to go through the can. Make sure you clear out any left over wire wool before you move on.