Secret writings are invisible writings that can be only seen after using any development technique which helps

in revealing those hidden messages. Secret writings is being used since the middle of the 20

century for hidden

messages. Secret writing was a source of communication for Prisoner’s. Invisible inks like biological fluids,

vegetable juices, fruit juices can be used to write the hidden messages. These messages becomes visible when

Invisible inks are used for secret writings. These are fluids used to write hidden messages that do not appear

unless exposed by a revealing process. Invisible inks can be classified into 3 main categories – those that are

revealed by heat, those that are revealed by chemical reactions, those that are visible under ultraviolet light.

Some common household invisible inks are diluted fruit juices, vinegar and laundry detergent, all which can be

applied by a paintbrush, special invisible ink pen or even a toothpick. The chemical processes of invisible inks

are well known, so a variety of detection methods exist.

Secret writing is any means of written communication whereby a spy conceals the actual written text, whether

it is enciphered or encoded or not. Codes and ciphers are sometimes mistakenly placed under the heading of

“secret writing”, but this is accurate only if that expression is taken in its most general sense, as writings that are

The experiment of secret writing comprises of dipping a paint brush in invisible ink and writing on a piece of

blank white paper. At the point when the “ink” dries, it will be undetectable to the bare eye, however in the event

that the paper is held up to a direct warmth source, for example, a light, a radiator or an iron utilizing UV light

to disentangling imperceptible composition.

Historically, invisible inks were utilized as a part of times of war by governments and extremists alike. The

utilization of secret writing has declined since the middle of the 20

century for some reasons, most critical of

which is the sheer volume information that knowledge administrations must transmit and process.

For conducting this research, writing samples like Milk, Onion juice, Soap water and Urine are used. Blank

2. UV light

This research is conducted in 20days. So, 40 samples are prepared using above mentioned inks. 20 samples are

used for decoding the message using heat method and other 20 samples are used for decoding the hidden message

using UV light.

Ignite the candle using matchstick. The paper is placed on top of the candle. Move the paper slowly horizontally

and vertically. After a few minutes due to the heat, the hidden message turns to brown color which can be seen.

The sample is placed in UV chamber after switching on the light. Observe the sample in both UV long and UV

short. The hidden message becomes visible.

Table 2- Visibility under UV long and short

decreased in onion juice, milk and urine samples when they are exposed to heat. When it comes to soap

water the visibility decreases from 19

day.

water are exposed to UV long. And when the onion juice is exposed to UV long, the hidden message

becomes clearly visible.

is no visibility in soap water & visibility of milk decrease from 2

day.

Secret writings can be written with body fluids, vegetable juices, fruit juices etc. They can be deciphered using

heat, chemicals and UV light methods. When the samples are exposed to heat, the secret message turns to brown

colour because these fluids alter the fibers of the paper and weakens the paper.

When samples are exposed to UV light, the secret message becomes visible due to their fluorescence nature.

Based on the results obtained, it could be concluded that the best method for deciphering secret message is

heating method. Because the secret message becomes clearly visible and almost all the invisible inks can be

visualized. In UV method, we cannot visualize all the invisible inks and secret messages are not clear.