I collected pressed pennies the last couple trips (back in '07) and I purposely took the really clean, shiny ones. They look a lot better and they still look nice even a few years later.
So, if you wash the older ones in coke, it's supposed to make them shiny?
Yes, it does! But make sure the coke contacts all surfaces...if they are stacke on top of each otherm in the glass of coke, it won't be as noticable where they are touching another penny. I believe it is the citric acid, but not sure...I also read that coke is good for cleaning toilets for the same reason..though I've not tried that one personally!
The coke won't make the old pennies shiny and light colored like the new ones, because they have a different chemical composition.
As to the content, Wikipedia says:
"The penny's composition was changed in 1982 because the value of the copper in the coin started to rise above one cent.[9] This was mainly caused by inflation. Some 1982 pennies use the 97.5% zinc composition, while others used the 95% copper composition."
It is the zinc that causes the streaks in the penny after it is pressed. You can actually tell the difference, as the new pennies are much lighter weight than the older ones, and sound different when dropped.
The new ones might stay shinier longer, but they will often have the dark streaks running through them after pressing, which may diminish the appearance of the pressing effect. This is because the copper is only a coating on the outside of the coin, and zinc is on the inside.
Too much information? lol
Whichever issue of penny you choose to use, it is always a fun thing to do at the park and doesn't cost a lot.
