Take some lemon juice, add a little bit of water and you have invisible ink!. Wait for it to dry and then place close to a lightbulb and writing or picture will appear. Here is our artwork:

Then I put my paper close to a lightbulb to magically reveal what was there, but nothing happened 🙁 Then I realised the problem, unlike when I was younger, my new LED lightbulbs are not hot! So we used a candle. PLease note, when using a candle you should be careful not to burn the paper!!

So we decided to test the 2 concerns when had about the first experiment.

1. we had used fake coke
2. coins different to the ones from my own childhood

We set up a second experiment, using both Real and Fake coke and using both Czech and English coins. We even managed to find an old English one pence piece that was from 1971 and therefore mage of 97% copper instead of just copper plated to see if that would make any difference.

After:

To start with we were a little disappointed, it seemed that the coins just got dirtier, not cleaner and you can see from the picture above. But then the children had the idea wipe the coins with a cloth and we were very pleased to see that the coins had been cleaned by the process.

After wiping.

Conclusion

Both real and fake coke is good for cleaning money! Fortunately none of the children can to the conclusion that if it is good for cleaning coins, it is probably good for cleaning other things, like TEETH!!! We decided to put the coins back in the coke and leave them until the end of the week to see if anything interesting happened.

Here is what happens when you add put Mentos into a bottle of Coke!

This is an experiment we did when I was at school, so a couple of years ago now! Take a copper and leave it in coke overnight, the next day it comes out clean, if you leave it longer I remember the coin would actually start to dissolve!

Conclusions.

All that seemed to happen is the the ones that where in the coke over night look even dirtier than they did before!The 10 czk coin seems to be effect worse than the 20czk. This could be because it is copper platter and the 20 is brass platted.

Differences between now and my childhood experience:

1. we use coca-cola when I was a child, not generic coke
2. pre-1992 UK coins (1p and 2p) where 97% copper, rather than copper plated

Therefore: we should do this again with real coca-cola and see if we can find a pre-1992 English coin!