Simple Techniques to Reveal Invisible Ink in Forensic Science

 

Sushma Upadhyay¹*, Farheen Fatima²

¹Assistant Professor, Department of Forensic Science, Guru Ghasidas Vishwavidyalaya, Koni, Bilaspur (C.G.)

²MSc Department of Forensic Science, Guru Ghasidas Vishwavidyalaya, Koni, Bilaspur (C.G.)

 

ABSTRACT:

Secret writing is a hidden writing which is used to convey a message as a means of communication. Invisible inks are used to write secret messages such as fruit juice, vegetable juice and by some chemicals also. This paper is about secret writing which can reveal from heating and how it is important in forensic science. The current research paper comprises of some samples which will help to specify and identify the secret writing and then they visualised by physical method and chemical method.

 

 

 

INTRODUCTION:

Secret writing is used in the middle of twentieth century as to convey messages to third person in invisible form. 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."^[1]

 

Prisoners used this secret writings as a means of communication by the use of invisible inks. Invisible ink is the ink which is not naked by the eyes it can only be reveal by some physical and chemical method.^[2]

 

Invisible ink can be categories by three types which can reveal from heat, chemical and by uv-light. Invisible ink include such as biological fluids (blood, milk, saliva, sweat and urine), chemical fluid (vinegar, saline, baking soda), vegetable juice (garlic, ginger, onion, potato, lemon) and fruit juice (apple, orange).^[3,4]

 

The simplest invisible ink experiment consists of dipping a brush in vegetable juice, biological fluids and different chemicals and writing on a piece of blank white paper. When the "ink" dries, it will be invisible to the naked eye, but if the paper is held up to a moderate heat source such as a light bulb, a radiator or an iron, lighter or burner and using UV lamp to deciphering invisible writing.^[5]

 

Ink developed by heat:

Iron the paper, set it on a radiator, place it in an oven for a minute or hold it up to a hot light bulb or can use a spirit lamp or lighter.^[6]

 

Ink developed by chemical reaction:

These inks are sneakier, because you have to know how to reveal them. Most of them work using pH indicators, so when it doubt, paint or spray a suspected message with a base like an acid lemon juice.^[2,6]

 

Ink developed by uv-light:

most of the invisible ink gives characteristic fluorescence like in case of detergents.^[1,6]

 

Methodology:

Aim:

To bring out the secret writing from the paper.

 

 

Material required:

Cotton swab, spirit lamp or lighter, UV lamp, paper, electric iron or candle, phenolphthalein reagent, iodine and silver nitrate solution etc.

 

Samples:

This paper comprises of ten samples in which secret writing is used as a hidden message in the form of invisible ink such as vegetable juice (lemon, ginger, garlic, onion), fruit juice (apple, orange), biological fluids (blood, saliva, sweat, milk) and then they are deciphered through physical and heating method.

 

Table no. 1: Vegetable Juice

S.no	Fluids	Sample	Methods	Results
1	Vegetable Fluids	LEMON JUICE	Heat UV  IR	Y Y  N
2		ONION JUICE	Heat  UV  IR	Y  Y N
3		GARLIC JUICE	Heat  UV  IR	Y Y N
4		GINGER JUICE	Heat  UV  IR	Y  Y N

 

Table no. 2: Fruit Juice

S.no	fluids	Sample	Methods	Results
1	Fruit juice	ORANGE UICE	Heat  UV  IR	Y  Y  N
2		APPLE JUICE	Heat  UV  IR	Y  Y  N

 

Table no. 3 : Biological Fluid

S.NO	FLUIDS	SAMPLE	METHODS
1	Biological fluids	MILK	Heat  UV  IR	Y  Y  N
2		SALIVA	Heat  UV  IR	Y  Y  N
3		SWEAT	Heat  UV  IR	Y  Y  N
4		BLOOD	Heat  UV  IR	Y  Y  N

 

RESULTS:

Biological Fluids:

Biological fluids include milk, saliva, sweat and blood when heated the invisible message appears in brown color. Biological fluids under U.V. lamp were visible as blue colour fluorescence.^[6]

 

Fruit juice:

Secret writing written with fruit juice (apple, orange) turn into brown in colour when heated. Chemical fluids under U.V. lamp were visible as blue colour fluorescence.

 

Vegetable Fluids:

Secret writing written with vegetable fluids (onion, garlic, ginger, lemon) visualized by heat was visible in brown color. Secret writing written with vegetable fluid when placed under U.V. lamp was visible as blue colour fluorescence.^[6]

 

CONCLUSION:

Secret writing samples are deciphered by using physical method and by heating method. Heating method is best to reveal secret writing from paper. Secret writing written with biological, fruit juice and vegetable juice are examined properly and revealed by heating method.

 

REFERENCES:

1.       Sharma B.R, Forensic Science in Criminal Investigation and Trials,Delhi,2005;4^thed: pp. 611-624.

2.       Lee J, Kong TY, Kim B, Jeon OY.Invisible ink mark detection in the visible spectrum using absorption difference. Forensic Science International.2014;236:77-83.

3.       Gardner, Martin. Codes, Ciphers, and Secret Writing. Pocket Books, New York. 1974.

4.       http://www.artofmanliness.com/2011/09/09/man-knowledge-the-history-of-invisible-ink/ (2013)

5.       Wilson R. Harrison, Suspected Document, 2008;(3), pp. 494-533.

6.       World Wide Web: Andharmule D, Kapoor N, Badiye A. An Evaluation of Some commonly used Methods for Visualization of Secret Writing: A research article. Available from : URL:

7.       http://www.isca.in/volumes-and-issues/2013/vol-1-issue-3.

 

 

 

Accepted on 18.09.2017        © RJPT All right reserved

Research J. Pharm. and Tech 2017; 10(12): 4209-4210.