Invisible ink experiments with lemon juice involve acidifying paper (writing with lemon juice) which causes your writing to darken in the oven – that part of the paper is less heat-resistant. The new heat-sensitive inks in the Frixion pens are different: they become clear above 60°C, and their colours return at around -10°C.
Let’s Discover: Switchable Ink
It’s time to make use of the winter weather we’ve had lately and use those chilly temperatures to get the most out of this month’s experiment! Let’s Discover by taking a fresh crack at the ever-popular (but usually tricky) invisible ink.
You will need a specific product to try this out: a Pilot Frixion Ball pen. While we generally stay away from endorsing particular
products, it’s an essential and inexpensive key to this experiment.
Try it! Draw a big square on a piece of paper or fabric with a regular pen or marker, and write a secret note inside it with your special pen. You can now heat the paper or fabric with an iron (with supervision) or by just rubbing something like an eraser over the writing. The ink will disappear, and the remaining square will remind you where it was. If you put it into the freezer, the writing should return. If your freezer isn’t cold enough, the outdoors in Nova Scotia certainly is in February, so take it outside for five or ten minutes. You can try lots of different ways of writing secret messages and creating temperature-sensitive art!
For another cool activity for the whole family, check out our newest travelling exhibit Ends of the Earth: From Polar Bears to Penguins, to explore the North and South Poles, and their awesome animal inhabitants – polar bears and penguins. It looks cold, but trust us, it will get your brain warmed up!