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Watermark Writing

Watermarks are easy to make and provide a novel, little-known way to write secret messages.

What you’ll need

  • 2 sheets of blank paper
  • Ballpoint pen or pencil

    • What you do

    Dip a sheet of blank paper in water. Place it on a smooth hard surface such as a windowpane or mirror and cover it with a dry sheet.
    Write on the dry sheet using a hard lead pencil or ballpoint pen and firm pressure.
    Discard the dry sheet. You will find the writing clearly visible on the wet one. The writing will vanish without a trace when the paper dries, but will reappear when the sheet is dipped in water.

    What happened?

    Pressure from the pen on the dry sheet of paper alters the fibres of the wet sheet beneath. This alteration is invisible when the sheet is dry, but becomes visible when it is wet again.
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