Which pen was used to make the forgery? Find out in this experiment!
Ingredients and equipment that you will need
Permanent black felt pen
Washable black felt pen
A shallow dish or tray of water
Method and further information
Write a pretend cheque on blotting paper, using a permanant black marker. Then get someone to forge it with washable felt pen.
Hold the cheque upright in a dish of shallow water – the easiest way to do this is to roll it into a cylinder held with a paperclip, then it will stay up by itself.
The permanent writing stays where it is, the washable ink runs up with the water and separates into different colours. You can very clearly see that it has been forged.
You can try different washable pens and show the difference between them, so you can identify which pen was used for the forgery.
Be careful – you should ask an adult to help you with these experiments. Do your experiments in old yoghurt pots, jam jars or bottle tops. Don’t use cups or glasses in case someone thinks it’s a drink.