Use These Inks to Increase Security

In addition to the many substrates, or paper that is available for the printing of security labels, there is also another layer of security that can be applied: the use of security inks. Indeed, today’s technology has seen the development and successful use of many ink types.

Solvent Sensitive

This type of ink offers some sort of visible change when it’s been tampered with. In this case, ‘tampering’ refers to the application of some sort of solvent to the ink in an attempt to remove information printed in the document. Solvent sensitive ink will change colour once a solvent has been applied to it. Some of the documents on which solvent sensitive ink is used include cheques and watermarks.

Fugitive Ink

This type of ink works in much the same way as its solvent sensitive counterpart, causing some sort of visible evidence of tampering once something has been applied to it. In the case of fugitive ink, any water or other liquid that is added to this ink will cause it to smudge the area or pattern it’s been applied to. Even wetting the finger with saliva and running it across fugitive ink can be enough to cause it to smudge.

Optically Variable

Also known as OVI, optically variable ink works much in the same way as a holographic image does, changing colour depending on the viewing angle. The most common colour shifts for OVI are red which changes to purple, and brown that changes to green. The secret is in its content of millions of metal flakes. This kind of ink requires printing in a heavyweight. Typically, OVI is used over small areas such as on currency or on a passport, as this ink is quite costly.


Thermochromic ink is temperature-sensitive, which makes it an ideal solution for a wide variety of applications. Thermochromic ink disappears at a certain temperature and reappears when its original temperature has been restored. This ink type is available in 15°C, 31°C and 45°C. This is so that the ink can retain its security in more than one temperature. For example, a 15°C level ink stored in 31°C temperatures would disappear.

This type of ink is also available in a ‘permanent change’ variety. When it reaches its colour-changing temperature, it doesn’t revert to its original colour.

Secondary Fluorescing

This ink type will only reveal itself to have been tampered with when UV light is applied. It will also glow in the absence of light when it has been tampered with. This type of ink offers a second layer of protection. For example, secondary fluorescing ink may appear as neon green under UV light, but then show bright red if it’s been tampered with.


The authenticity of a product can be verified using biometric ink. This ink type contains DNA tagging agents that can be read by a machine that determines its authenticity. They can also be tested for authenticity by applying a reading solvent. Biometric ink can contain a wide range of varying properties, which only increases the security of the items the ink is used on.


Like its optically variable counterpart, magnetic ink contains small flakes, but of the magnetic variety. Magnetic ink is primarily used for the purposes of numbering and sterilisation. The flakes are read by a machine to determine their number. The MICR numbering on a cheque is commonly printed with magnetic ink, and contains various information including cheque and account number and the bank’s sort code.

These inks can be found in and on many of the goods we use. They can also be chosen when you need to ensure that your products are authentic and/or safe for consumers to use.

Security Ink Types

When considering the printing of security labels, you should know that there are several different types to choose from. To be exact, there are eight types of ink that are used for security purposes. The most common applications for the use of security ink include cheques, passports and security documents.


This ink type is also known as solvent sensitive. Reactive ink will tell a person if any alteration has been attempted. Attempts to remove this type of ink usually occur on items like cheques, where variable printed information exists. Reactive ink is most commonly used in the security of printed watermarks.


Thermochromic ink is temperature-sensitive, appearing or disappearing when exposed to varying temperatures. This type of ink is available in a wide range of sensitivities, but the most common temperatures are 45, 31 and 15 degrees Celsius. When considering this ink, it’s important to determine the conditions that the ink will be exposed to, as ambient temperature can affect visibility.

Optically Variable

This type of ink is also called OVI. Optically variable ink has tiny flakes of metallic film which changes the colour set as the viewing angle is altered. This very expensive option needs to be printed in heavy weight for optimal effectiveness and usually appears on currency, passports and the like. Most commonly, the colour of optically variable ink will change from brown to green and vice versa, or red to purple and vice versa.


In the UK, invisible ink is used for the purposes of document protection as well as cheque printing. Invisible ink’s most common form is the invisible ultraviolet type, which is only visible when the print is placed under a black light source. The only way to make this ink visible under a black or UV light source is to apply it to a UV dull substrate such as paper or card stock.

Water-Based Fugitive

Fugitive ink reveals tampering much in the way that reactive ink does. When an attempt is made to alter some aspect of a document using water or another liquid, fugitive ink will run, effectively smudging any area or printed pattern. Fugitive ink is found on cheques, and all that’s needed to test for this type of ink is to wet your finger with saliva and run it across the cheque’s printed background.


Where security for serial numbers and other numerical sequences is desired, magnetic ink is the typical solution employed. This type of ink contains tiny magnetic flakes which communicate with an electronic reader to verify a document, such as a cheque. Magnetic ink is in use on the MICR numbering portion of cheques manufactured in the UK. The MICR number contains sensitive information including account number, sort code and cheque number.

Secondary Fluorescing

Where fluorescing ink glows or becomes visible under UV light, secondary fluorescing ink does not do so unless some sort of alteration attempt has been made. This ink is used to protect against alteration and tampering. Usually, secondary fluorescing ink will appear green when exposed to UV light, but will include a red secondary shade which will show if any tampering has been attempted.


As its name suggests, biometric ink contains DNA tags. A machine can read these tags, or they can be manufactured to react when they come into contact with a particular solvent. Biometric ink works best in situations where verification of a genuine product is needed. Biometric ink can also contain a different set of biometric properties for each batch of documents that is printed. Validating the authenticity of a product marked with biometric ink requires specialist methods to be used.

Understanding Black Ink Types

If you thought there was only one kind of black ink that could be used in your printer, you are not alone. Many people aren’t aware that there are actually two kinds of black ink: matte and photo.
Matte black ink is most commonly used on non-coated paper, and will usually print darker. However, if used on coated paper such as photo paper, matte black ink will not dry.

Photo black ink was born when manufacturers were unable to get matte black ink to dry on coated paper. For this reason, photo black is used in applications where paper has been coated with semi-gloss, glossy, lustre or semi-matte layers.

Printing With The Correct Ink, Correctly

The printer drivers of the computer which communicates with the printer are what usually determine which ink is best for the type of paper it will be printed onto. Interestingly, this choice may or may not be available in the print dialog box. The good news is that there are printers which will switch ink types as necessary, depending on the type of printer paper that has been inserted.

Experimentation can be another way to ensure that the right ink has been chosen for the inkjet labels being used. The choice between photo black and matte black ink can be made manually if this option is available in the printer window. While a print job using photo black on uncoated paper may cause the print shade to be darker, it is highly unlikely that doing this will completely ruin a print job.

Because matte black ink will not dry properly on coated paper, printing in this way will require caution, as smudging can easily occur. In this case, it is probably best not to consider a document printed in this way to be a final product.
Should ink not dry when you print with matte black or you don’t observe an increase in darkness, photo black ink may be your best option? On the other hand, if the ink dries and appears richer and darker, matte black may be the better choice.

Printing with Older Printers

If you own an older printer, you may need to clean or purge the printer’s heads and lines before switching from one ink type or another. Because a high loss of ink is common with older printers, it may be best to choose the best ink for your inkjet labels printing job and then keep using that ink. As well, consider the cost savings of purchasing a new printer versus repeated ink loss with an older machine.

If You Can’t Choose Between Matte Black and Photo Black

If you want to have the freedom to use both types of black ink when you need to, then it may pay to purchase a new printer. Most modern printers will have one of the two following features:
Two sets of heads, lines and slots for two black ink cartridges;

Two sets of lines and slots, but only one head, shared by both black ink cartridges. If the printer is of the first variety, no further action is required, as ink selection will be made automatically. Printers of the second variety will require ink type to be changed by choose from a menu or via a button located on the printer itself. This will result in ink loss, but it will be minimal.

The system used by your printer can easily be identified; simply look for a ‘change ink’ button on the printer itself, or within the printer’s menu. The system type can also be identified by consulting the printer’s manual.