In life, sometimes there is such a situation when it is necessary to give someone a secret letter, let it be for the sake of some prank, for the sake of a game, but sometimes adults use this method of sending letters. This method was used by high-ranking officials, among whom was
Comrade Vladimir Ilyich Lenin (Ulyanov) himself and Ivan the Terrible. At that time it was widely used invisible ink, but today, in the century high technology, it is rare to find such a method of encrypting messages. But still, let's look at it, maybe it will be useful to someone.
How to make DIY invisible ink
This method of making invisible ink is affordable for everyone, because the cost of materials is very minimal. So, let's take the necessary materials:
- Milk or lemon juice (optional) You can also take Apple juice;
- Brushes for drawing;
- , you can also do it yourself;
To create a secret letter, at the beginning you need to take a container and pour milk or lemon juice into it. Take a clean sheet of paper and a brush. When you have prepared everything, you can safely draw letters or other patterns. After everything has been drawn, the paper must be thoroughly dried. It will be perfectly noticeable when your drawn patterns disappear and the sheet of paper turns white again. After the final drying, your letter can be sent to the addressee.
How to read invisible ink
The easiest way to read is to heat the sheet. To do this, take a candle and bring a secret message to the fire. Follow the safety precautions so that the sheet does not catch fire, hold it at a distance of approximately 10 centimeters above the candle flame, moving the letter in different directions. Do not abuse the heat, so as not to damage the message.
Since ancient times, mankind has tried to invent invisible or, as they are also called, sympathetic ink, which are not visible to the eye in normal conditions, but they begin to appear after exposure to any chemical elements, heating, ultraviolet rays. They were used to send secret messages, to keep important information, secret correspondence.
In ancient times, these were commonly available substances that could be found in every home. For example, cryptography, carried out with the help of milk, lemon juice, rice water, wax, apple and onion juice, swede juice, enjoyed great success. Later, options for making sympathetic ink appeared using aspirin tablets, copper sulfate, iodine, and washing powder.
Modern UV ink
Science does not stand still, so in our time you will no longer surprise anyone with invisible industrial ink. Compounds that glow under ultraviolet lamps. There are even pens with UV ink on sale, which can be found in spy shops.
An alternative to such a pen can be invisible anti-counterfeiting paints and pigments. They are powdered substances that can be used to mark banknotes, securities, clothes. In daylight, the powder is completely indistinguishable, but in ultraviolet light, every grain or powder becomes noticeable.
How to make invisible fluorescent ink at home
A good fluorescent ink can be a regular laundry detergent containing optical brighteners. Having diluted the powder with a small amount of water, you can begin to write a secret message. The dried solution will not leave prints on paper, but it will be perfectly visible in the light of an ultraviolet lamp.
Also can be purchased separately. As a rule, they are used to give whiteness with a bluish tint to clothes, fabrics, paper intended for printer printing. The powder can also be used to create sympathetic ink. These inks show up on all types of paper.
Another way to make invisible ink is to use aspirin tablets and alcohol. In a small amount of alcohol, 2-3 aspirin tablets should be dissolved. If a precipitate remains during the dissolution, then the liquid should be filtered. After that, you can start secret writing. Such ink does not glow on all types of paper, this method is not applicable if you write on printer paper.
You can also use the following preparations to prepare ink, which you can try to purchase at a pharmacy:
- curcumin;
- quinine sulfate;
- tripoflamin.
Fluorescein sodium salt can also be used, but its native color may stand out on white paper after application, so this ink is not considered invisible.
Q&A No. 20
Added: 12/05/2013
From time immemorial, almost immediately after the appearance of writing, people began to think about the possibilities of preserving the secrecy of correspondence. Of course best remedy Invisible ink was used to solve such problems. Cryptography, applied to paper with the help of special substances, made it possible to hide a lot of different secrets. A meaningless entry, visible to others and applied over the disappeared words, carefully kept its secret until a “craftsman” was announced who was able to read the text hidden between the lines.
Today, invisible ink, also called sympathetic ink, can be made at home. You can use this unique invention for various purposes, but in most cases, it is the basis of all kinds of pranks. For the maximum masking of the notes with invisible ink, in order to hide the slightest hint of their presence, something else can be written on top of such a colorless text, for example, a poem by Pushkin.
There are several recipes for making sympathetic ink:
First way
In the old days, liquids were used as disappearing ink, which, after drying, did not leave the slightest trace on paper: white wine, beer, milk. To develop a recording made from the above "ink", you will need ordinary ashes. To enhance the effect, the paper can be lightly dampened by breathing before being treated with ashes.
Second way
Very good results can be achieved using swede juice, apple juice, onion juice, citric acid. For the manifestation of messages written in such invisible ink, it is enough to hold a sheet of paper at a distance of ten centimeters from the fire. If you do not want to come into contact with fire, you can simply hold the paper under a hot iron.
Third way
Starch can also be used to make invisible ink. To read the inscription, the paper should be treated with a weak solution of iodine. As you know, under the influence of iodine, starch turns blue.
Fourth way
Ordinary washing powder can also be a good base for creating colorless ink. To read the inscription, just place it under the source ultraviolet radiation. As a rule, such lamps are used in nightclubs, solariums, devices designed to detect counterfeit banknotes.
Fifth way
Often in extreme conditions the role of ink was performed by ordinary saliva. A weak ink solution was used for development.
Sixth way
Using a syringe to inject a small amount of a colorless indicator of phenolphthalein into a goose quill, you get a good improvised pen. To develop the recording made by her, you need to use a swab dipped in any alkali (sodium hydroxide or potassium hydroxide). The letters will instantly acquire a crimson color.
Seventh way
You can write colorless messages with rice water. To develop the record, it is enough to process it with a weak alcohol solution of iodine. As a result, the letters turn blue due to the starch contained in the rice.
Eighth way
You can make notes on paper from a highly concentrated solution of cobalt chloride. Such text appears beautiful blue color when heated. Moreover, later such a record can be “forced” to disappear again. To do this, just breathe on it or hold it over the steam.
Ninth way
Dextrin and iodine will also help create disappearing ink. Dextrin is a substance obtained by heating starch. 3 grams of dextrin are added to 30 ml of iodine and passed through filter paper. The resulting blue ink write some text. After a couple of days, the record will disappear without a trace, and it will be impossible to restore it, due to the volatility of iodine.
Cryptography is good and interesting, but maybe you should move away from cryptography and turn to steganography, that is, hide the very fact of the message by writing it with invisible ink?
Already here, but let's put together a longer list ...
The disadvantage of invisible ink is that they were mentioned by Ovid and Philo of Alexandria. That is, it is enough to check the correspondence once to find the message. The same case described here with Lenin and milk was known to the tsarist secret police and Lenin's correspondence was successfully read by the enemy.
However, invisible ink has been and has been used for many centuries, they were popular not only in the Middle Ages, but also in the First World War and even, it happened, in the Second, despite the spread of radio. Actually, they are still used, but in other areas - for example, they mark banknotes to identify the bribe taker.
So, let's look at invisible ink by developing methods:
Heat development of ink
This is the oldest method and the most primitive. Only a lazy spy from pre-Christian times did not know about him.
However, there is a twist in it - if the enemy read the letter, then it definitely will not reach, and what has reached is unread. I think Lenin used this very property when sending a letter with milk.
Here you can use:
1.
Honey or sugar (it darkens at caramelized temperature).
2.
Lemon, apple, onion (organic acids react with paper when heated).
3.
Milk (lactose dehydration).
4.
Serum.
5.
Soap (carboxylates are oxidized).
6.
Wine vinegar.
Here, alone, you can add an item 7
, cobalt chloride.
The fact is that in the first six paragraphs the inscription appears irreversibly and it is impossible to deliver the letter to the addressee in this form - it is clear that it was read. Cobalt chloride, when heated, becomes of blue color and when it cools the color disappears. Undoubtedly, it is good to add it to the paint to enamel teapot to see if it has cooled down, but for cryptography ...
Chemical ink development
Here we will try not to mention the ink that reacts to heat.
1.
Phenolphthalein, the most famous acid-base indicator. Accordingly, it is necessary to develop letters with substances to which it reacts. The easiest way is to take soda or potash with an alkaline reaction.
Quite a hit option, because phenolphthalein is obtained from phenol, which the hit man will still have to mine in order to get carbolic.
The disadvantage is that both acids and alkalis are too simple substances that the enemy will have available.
2.
Ammonia, that is, ammonia. It is manifested by a ph indicator made from red cabbage (the technology is primitive, google "red cabbage water").
Method .. let's just say - bad.
Ammonia was expensive in ancient times, and the presence of cryptography is easily determined by smell, which is generally out of the question.
3.
copper sulfate. It occurs naturally as the mineral chalconite. Manifested by sodium iodide, sodium carbonate, ammonia hydrate or red blood salt.
A perfectly viable option. The main thing is the secrecy of obtaining chemicals for manifestation.
4. Lead nitrate. The compound has been used since the 16th century. Manifested by sodium iodide. For ancient times, the level of secrecy is very high.
5. ferrous sulfate. Manifested by sodium carbonate or red blood salt. ancient method.
6. Starch. Manifested by iodine compounds. A very interesting method, probably the most interesting. Starch is available, in fact, at all times. But it is still very desirable for a hitman to receive, for and not only.
7. Salt. Manifested by silver nitrate ("hell stone", "lapis"). Something tells me that in the Middle Ages this method was very well known.
8. Cerium salt oxalic acid. It is manifested by manganese sulfate or hydrogen peroxide. For a hitman, it has a purely academic interest.
UV ink development
Here the question is not in the substances with which they write, here the question is precisely in the ultraviolet. Now there is a detector at any checkout in a supermarket, but it’s more difficult for a hitman to build one.
But let's take a look at the ingredients:
1. Liquids from human body- saliva, blood plasma. Well, for aesthetes - sperm (I just have a bad idea how to write to her, even with a pen). Nevertheless, the substances are extremely accessible, there seems to be no need to even continue.
2. Soap, lemon juice. But this is hardly suitable, because it is determined by heating. It is stupid to fence the ultraviolet detector in this case.
3. Sunscreen
4. Laundry detergent containing bleach.
Separately, there are several methods used in the First World War.
1. Taken raw egg, messages are written on its shell with vinegar. If the egg is boiled and peeled, then the letters can be seen on the surface of the boiled egg. The method is very niche - it works at short distances and is hardly suitable for the Middle Ages. Well, maybe so - to convey the news from the besieged castle (although this may turn out to be a lot).
2. A bunch of all sorts of methods with photographic paper, where a developer is corny in dark room, and the letter comes in black opaque paper. There are so many variations of this method that it is necessary to describe separately. Is it only necessary for the hitman?
During the First and Second World Wars in the USA and Britain, all suspicious letters were scanned with ultraviolet and infrared rays, treated with iodine vapor and ammonia vapor. The Americans so in 1918 caught a German saboteur.
Therefore, here's a snack for you - the requirements for ideal invisible ink, formulated by British intelligence in the First World War:
1.Miscible with water.
2. They do not have a pronounced odor.
3. Do not form crystals on paper, otherwise they can be seen in reflected light.
4. Invisible in ultraviolet.
5. Does not decompose or discolor paper (like silver nitrate)
6. Do not react to iodine or any common developer.
7. Potential ink developers should be as few as possible.
8. The ink must not react to heat.
9. Should be easily accessible and have at least one plausible innocent use in everyday life.
10. Not be a combination of several substances.
It is easy to see that points 7 and 10, as well as points 6 and 9, are incompatible with each other.
However, the last time the use of invisible ink was noted in 2008, when they discovered notebook, where al-Qaeda's phones were written in invisible ink.
Project for elementary school. Spy (sympathetic) ink
Brief abstract of the research paperKnowledge of the secrets of cryptography - fascinating process. In this work, the author describes what invisible ink is, the history of its origin; an attempt was made to prepare several types of sympathetic ink at home and apply them to write invisible text. The hypothesis put forward that if "spy" ink is made in secret laboratories that develop special equipment for spies, then some of them can be made at home, was fully confirmed during the experiments.
This work will be of interest to everyone who loves various secrets.
Table of contents
Introduction 3
Chapter 1. Theoretical study problems 4
1.1. What is invisible ink 4
1.2. History of Invisible Ink 4
1.3. Kinds of sympathetic ink: 5
1.4. How to make invisible ink at home 6
Chapter 2. Practical study of the problem 7
2.1. Questioning classmates on the topic of research 7
2.2. Writing tools and accessories 7
2.3. Testing invisible ink 8
Conclusion 9
List of information sources 10
Annex 11
List of information sources
1. List of references
1.1. Aleksinsky V. N. Entertaining experiences in chemistry. - M .: Education, 1995 - 96s.
1.2. Lavrova S.A. Riddles and secrets of ordinary things. - M .: White City, 2006 - 48s.
1.3. Lavrova S.A. My first book. Entertaining chemistry for kids. - M.: White City, 2009 - 128s.
1.4. What? What for? Why? The big Book questions and answers / Per. K. Mishina, A. Zykova. - M .: Eksmo, 2007 - 512s.
2. Other sources of information
2.1. invisible ink. Disappearing ink. [Electronic resource].
2.2. Do it yourself, with your own hands. invisible ink. [Electronic resource].
2.3. Sympathetic (invisible) ink. [Electronic resource].
2.4. How to make invisible ink? [Electronic resource].
2.5. Who Invented Ink? [Electronic resource].
2.6. What is sympathetic ink for? [Electronic resource].
2.7. Children's lessons. How to make invisible ink. [Electronic resource].
Application
Attachment 1
The results of the survey of classmates
Have you seen spy movies?
Do you know about invisible ink?
What can invisible ink be made from?
Would you like to learn how to make invisible and disappearing ink?
How to make invisible ink
Appendix 2
Sympathetic ink recipes at home
Invisible ink from a lemon - squeeze the juice of half a lemon and dilute it with the same amount of water, show with heat;
Invisible onion ink - prepare onion juice and use it as ink, manifest the effect of heat;
Invisible ink from milk - take milk and use it as ink, dry it, show it over a candle or lamp;
Invisible soda ink - prepare a concentrated soda solution - 1 teaspoon per 10 ml. - 2 - 3 teaspoons of water, move everything around, use as ink that lasts a long time, develop with heat.
Invisible ink from starch - prepare a solution of starch with water, move everything and cook until a homogeneous mass is formed, use it as an ink that lasts a long time, show it with an iodine solution (1:10).
Annex 3
Experiment 1: Making Invisible Lemon Ink
For this we need: half a lemon, a glass, a brush, White list paper. Squeeze the juice from the lemon into a glass, add the same amount of water. Dip the brush in a solution of lemon juice and water and write something on paper. After the inscription is made, it must be allowed to dry. To develop the inscription, it is necessary to heat a piece of paper, for example, iron it with a hot iron. Citric acid darkens when exposed to temperature and thus my ink becomes visible.
Experiment 2: Making invisible ink from onions
For the experiment, we need the same as for the previous one.
Take half an onion, grate it on a fine grater and squeeze the juice through a piece of gauze into a glass. Apply onion juice with a brush on paper, wait for drying. When dried, the onion juice is a little noticeable on paper, and has a not very pleasant smell, which makes this ink imperfect. We will manifest in the same way - by heating. Onion juice darkens when exposed to heat, and the ink becomes visible, turning brown.
Experiment 3: Making invisible ink from milk
Pour milk into a glass. Dip the brush in milk and write it on a piece of white paper. Let the milk dry. From the letters there will be no trace, no smell. We will manifest in the same way - by heating, since milk will change color when heated. The milk has really changed color.
Experiment 4: Making invisible ink from baking soda
It is necessary to prepare a saturated solution of ordinary drinking soda in water. Dip the brush in the baking soda solution and write it on a piece of white paper. Immediately behind the brush, the water evaporates, and there seems to be nothing on the sheet of paper. The secret writing is also very simple: by exposure to heat. When heated with an iron, dark brown text appears. Moreover, this text turned out to be the brightest and most uniform of all the previous ones.
Experiment 5: Making invisible ink from starch
Starch can also be used to make invisible ink. It is necessary to prepare a saturated solution of starch in water. I used, as in previous recipes, a brush. To read the inscription, the paper should be treated with a weak solution of iodine. As you know, under the influence of iodine, starch turns blue.
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