Page 35 - Veritas Vol 3, Issue 2

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Principle of Invisible Writing

The principle behind secret writing is that the carbohydrates present in various
invisible inks such as lime juice, milk, vinegar, fruit juices, and vegetable
extracts and in biological fluids such as sweat, saliva, urine, etc. are absorbed

into the paper, and when the writings are subjected to heat application, the
carbohydrates start to carbonise. This leads to the release of carbon atoms,

which in turn react with oxygen atoms, and an oxidation reaction occurs. This
oxidation process produces a yellow-to-brown colour, which is imparted to the

writings. Thus revealing the information.

MATERIALS REQUIRED

1. Invisible inks such as milk, lime juice, baking soda, and saliva.

2. Heat applications include candles, heat burners, and electric irons.
3. Miscellaneous-Q-Tips Buds, Paper, and Pencil.

METHODOLOGY

A total of three samples containing hidden messages were inked using different
inks, including saliva and milk (biological fluid), baking soda (chemical fluid),

and lime juice (vegetable fluid). The writings were created by dipping cotton
swabs or earbuds in different types of fluids. After being kept at room

temperature for a while, the samples were analysed. These samples were then
deciphered using different physical and chemical methods.

Samples-
Types of Fluids Used-

Methods of decipherment-

1. Sample (Milk)
Biological Fluid

UV light, heat, and chemical methods.

3. Sample (Baking soda)
Chemical Fluid
UV light, heat, and chemical methods.

VERITAS VOLUME: 3, ISSUE: 2 WRITER: ANOHA ANN CHERIAN