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Security Inks

A wide variety of security inks are available to use in conjunction with good security design to authenticate your document. It is important to understand what you are trying to achieve when selecting the right security inks.Security inks are available to protect printed materials in different guises.

What types of security inks are there?

Security inks are available to protect printed materials in different guises.

Invisible Ink: One of the most widely used inks is invisible ultra violet and will be revealed when the print is placed under a black lamp (or UV light source). The ink is invisible to the eye (covert) under normal lighting conditions. When passed under a UV lamp the ink glows and is used predominantly for cheque printing and document protection in the UK. It is relatively cheap and is available in many colours. The ink must be applied to a UV dull substrate otherwise it will not be visible.

Thermo Chromic Ink: Thermo chromic inks are sensitive to temperature changes and will appear or disappear at different temperature ranges. If you were to apply a finger and thumb to a 15 °C dark blue printed thermo spot the ink would disappear to nothing and as soon as you removed the heat source the ink would re-appear again. Inks come in various temperature sensitivities and common temperatures available are 15°C, 31°C and 45°C. An important consideration would be where the ink is to be located. In hotter climates you may well have to go for a higher temperature as the ink could be invisible from the ambient temperature itself. Some are available as a permanent change. e.g. when it has reached a temperature the ink colour does not reverse – this may be used on labeling for food product packaging where you could see if an item has thawed out and would be dangerous to re-freeze again.

Solvent Sensitive Ink (Reactive): As the name states, would present a visible indicator that the ink has been attacked by a solvent (usually attempt to remove variably printed information such as a cheque). You will mainly find this being used on a printed watermark or fine guilloche artwork design. Once a solvent has been applied the ink will change colour to show that alteration has been attempted.

Optically Variable Ink: OVI’s contain minute flakes of metallic film. As the viewing angle is altered the colour morphs from one to another. This needs to be printed with a fairly heavy weight to get the best results. The inks are very expensive and are usually printed in small areas. Such examples would be in currency printing and visa’s. The most common colour changes are brown to green (and vice versa) as well as red to purple.

You will also notice that the ink feels almost embossed on the substrate which is due to the amount of ink required to get the required effect.

Magnetic Ink: Magnetic inks are mainly used for serialization and numbering purposes. The ink contains small magnetic flakes and allows a number to be machine read. The most common application is cheque printing and you will find it on the MICR numbering portion of the bottom of a cheque. This will usually contain the cheque number, account number and sort code of the bank.

Biometric Ink: Biometric inks contain DNA tangents that can be machine read or react to a reading solvent. This allows for verification of a genuine product and each batch of printed documents can contain different biometric properties. These are completely covert but require specialist methods to validate the authenticity.

Fugitive Ink (water based): Fugitive ink works similarly to solvent sensitive ink in the fact that any form of alteration (with water or an aqueous solution) will make the ink run so that the printed pattern or area becomes smudged, therefore indicating that a forgery or alteration has taken place. These, again, will be found on cheques and if you are too wet your finger with saliva and wipe across the background, you would see the ink smudge.

Secondary Fluorescing Ink: This ink works in the same way as fluorescing ink however it will not glow or show under a UV lamp UNLESS alteration has occurred. This is a secondary measure to protect against tampering and alteration. Quite often you will have an invisible ink that fluoresces green under a UV lamp and a secondary ink that will fluoresce red so that tampering or alteration is obvious.

Security substrates such as paper and card

What are the different types of substrate?

Depending upon how secure you feel your documents need to be, you need to start any printing solution with a good quality substrate (security paper, card or stock) that offers basic security measures in itself. Some of these papers are readily available off-the-shelf from paper merchants and, when bought in bulk, provide a good basic level of security compared to the costs involved in other processes.

UV Fibers: The use of fiber optics in the transmission of light in the UV spectrum is gaining importance. Fields of application include, for example, the spectroscopic examination of ions and atoms; however, analytics also provides interesting application options. Further fields of application include laser medicine, such as in the treatment of psoriasis in dermatology or the correction of vision problems in ophthalmology.

Special Fibers for the UV Range

Our partner Poly-micro has developed a wide range of UV-suitable fibers that can be used for very short-wave applications. The R&D department was successful in making these fibers extremely solarization proof.

Security Threads: Security threads are widely used in banknote papers to deter counterfeiting. Incorporated at the beginning of the paper production process, they are inserted in the pulp during sheet formation. They can be fully embedded in the paper substrate or “windowed”, appearing and disappearing at regular intervals at the surface of the paper. In transmitted light, security threads appear as a continuous line. Effects carried by security threads have considerably evolved: from simple printing to eye-catching moving effects that are easier to identify. Security threads are one of the most reliable features to secure a paper note.

https://www.vinsak.com/product/vinsak-security-inks-substrates/