Sympathetic ink

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Sympathetic ink

The use of sympathetic (invisible) ink implies a recording that is indistinguishable under normal conditions, but appears after physical or chemical treatment.

The process of using good sympathetic inks includes the following nuances:

1. Recording is carried out on non-glossy paper, not of very high quality, of sufficient density. The color of the paper should be slightly grayish, and not perfectly white. If the paper has a low density, the ink will be very blurry. You can write on a blank sheet, or between lines of already written text (letters, books).

2. Recording is carried out with a pointed match, a toothpick, a thin rod of a felt-tip pen, or an ink pen. The main thing is that the pen does not scratch the paper.

3. Both before and after writing, the sheet is carefully smoothed on both sides in different directions with a piece of soft cloth to hide the traces of cryptography in the surface layers of paper.

4. The cryptographic sheet is steamed, and then clamped between the pages of the voluminous book and dried well. If the inscription is invisible, then everything is in order.

5. Next, on such a sheet write a letter or other harmless formula (for example, a poem).

Insuring yourself against amateur attempts to identify the cryptography using the “spear” method, you can use various tricks, including nitration of the paper (flashes with excessive heat) or recording with a light-emitting diode (LED) on highly sensitive photo paper (the writing is illuminated when daylight hits).

For the manifestation of cryptography, one must use the appropriate reagent and a suitable technique. Here, the developer itself is applied through a touch - wiping with a sponge (swab), through spraying from a spray bottle or in another accessible-optimal way. In temperature variations, ironing or heating near an electric lamp is involved.

As an ink for cryptography, you can use very many of the substances tucked into your hand: medicines, household chemicals, and even excrement. The following is a list of possible substances and methods for their manifestation. Concentration is established experimentally.

Substance, Method of manifestation:
Beer and White Wine

Lightly moisten the sheet with breath and sprinkle with ash from burnt paper.

Sugar water and factory apple juice

Same.

Onion and rutabaga juice

Heat.

Pyramidone (in alcohol solution)

Heat.

Astringent disinfectants for the mouth and throat

Heat.

Aspirin (in aqueous solution)

Wipe with a solution of iron vitriol (buy in a fertilizer store).

Phenolphthalein (laxative, make an alcohol solution)

Wipe with a solution of alkali (silicate glue, ammonia, caustic soda, hydrated lime).

Alum

Heat.

Diluted battery electrolyte (with conc. Sulfuric acid 10–15%)

Heat.

Wax (write with the pointed end of a candle)

Sprinkle and shake off with tooth powder, chalk.

Washing powder solution

UV light (currency probe, bactericidal lamp).

Saliva

Ink diluted with water.

Urine

Heat.

Milk

Heat.

A very convenient way of cryptography is the method of "water pressure".

Dampen a sheet of non-lined paper with water and place it on a mirror. On this sheet, put another, dry sheet and with a hard pencil or empty ballpoint pen write the necessary text. While the paper is wet, the text will be visible, and as soon as it dries, it will disappear. After the sheet becomes dry, some masking letter is written on it with ordinary ink. In order for the hidden message to appear, you just need to stick the sheet into the water and immediately pull it back.
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