We found the duller the penny the better the image showed up. I'd check with a coin collecter about cleaning the wheat ones. You can use regular dish detergent on dirty newer ones though.
I've used the shiny pennies and I think they turn out better. I don't have any hints for cleaning them. Have fun finding all the penny machines. They make a nice inexpensive souvenior.
c. aNN YOU SHOULD REALLY PREFER TO USE PENNIES THAT PRE DATE 1982. pENNIES MADE PRIOR TO 1983 WERE 100% COPPER (LOR CLOSE ENOUGH). ooooops sorry about the caps. there are copper cleaners out there at your grocery store on the dish liquid isle.
Does anyone know how many penny machines (approx) are in the MK? I am sure we didn't capture all of them last time. Also, I presume they are at the other parks. Is that correct?
Dip pennies in white vinegar for about a minute. Then clean them off with toothpaste. Rinse and pat dry. It will totally take off all the scum and make them nice and shiny.
We tend to just use whatever is in our wallet. That way we get a nice assortment! Sometimes the older ones show the design that is pressed into it, since they are not so "shiny"!
but I have a feeling it is all a matter of preference. So I would reccomend trying a couple of each and going from there!