‘Magic’ writing with colour changing reactions

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Reveal invisible messages or pictures drawn with aqueous solutions by spraying them with suitable reagents in this demonstration. Includes kit list and safety instructions.

In this experiment, the teacher prepares messages or pictures drawn on absorbent paper using a variety of colourless, dilute, aqueous solutions. When these are allowed to dry, they are rendered invisible. Students then observe how spraying the paper with solutions that contain different reagents – each of which reacts with one or more of the chemicals on the paper – reveals the hidden messages or pictures.

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