Safety & Security Unseen (Part I)

Steganography (the word is derived from the Greek for "covered writing") is the art and science that deals with various methods of secret communications, particularly those where the message is concealed, such as with invisible inks.

Such inks, standard tools of espionage in almost every military and political conflict throughout history, go back from as far as 430 B.C., in the Histories of Herodotus, to all recent wars, both cold and hot.

Invisible inks made news earlier this year when historians sued the Central Intelligence Agency (CIA) for refusing to release formulas for those inks used in World War I. The formulas, however, remain safe in CIA vaults because a federal judge sustained the agency's claim that, even after 85 years, publishing them could compromise national security.

As a result of advanced printing ink technology, invisible inks have found a new venue in business and commerce as a means of protection against fraud, counterfeiting, and theft. Though a number of security printing inks have been developed to foil criminal purposes, among the most ingenious are those that are invisible after printing, but which can be made visible through various means to prove the authenticity of a particular document.

These products are being used to authenticate a broad range of valuable commercial documents, such as stock certificates, bearer bonds, checks, lottery tickets, and vouchers. Also, particularly in light of recent terrorist activity, they are being applied to protect against the misuse of personal identification documents, such as Social Security cards, passports, visas, identification cards, credit/debit cards, automobile licenses, and vital business and health records.

"We produce several inks that are indeed undetectable to the human eye when dried after printing because they are formulated with transparent white ink vehicles," says Tom Jay, a vice president with Springfield, Va.-based SICPA Securink Corporation (sicpa.com), which specializes in security inks.

He says, "Requiring only minor press tweaking, such as small adjustments in roller settings or a change in fountain solution, they can be run with offset, flexo, and gravure printing processes in use today."

On most documents, invisible inks are used in spot applications. The authenticating image can be a company logo, government seal, or hard-to-duplicate graphic design, or it can be as simple as a block of ink that is positioned to be easily referenced by machine, exposure to a particular light source, or with the use of a chemical reagent.

SICPA's invisible inks include the following:

Invisible UV Fluorescent Inks—Used in documents as a covert security feature, they are colorless and transparent after printing, making them undetectable under normal light conditions. Applied by themselves or incorporated into another security ink, they fluoresce (become visible) under ultraviolet (UV) light. To further foil counterfeiters, the UV fluorescent effect is impossible to photocopy or digitally recreate. The inks can be applied by wet or dry offset, flexo, or gravure processes.

Pen Reactive Inks—Two systems are available, reversible and irreversible, mainly used to authenticate sensitive documents. Invisible when printed by either dry offset or letterpress, they are designed to develop color when touched with the appropriate chemical reagent, usually supplied in a special developing pen. In the irreversible formulation, the ink remains visible for up to a year, the reversible formulation becoming invisible again after a period of time.

Coin Reactive Inks—These inks offer instant authentication when rubbed with a coin or other metal object, or a Highlighter pen. The transparent (invisible) version is printed by wet or dry offset in a discreet area of a document, usually where criminals are most likely to attempt an alteration of intrinsically valuable documents, such as laser-printed checks or gift certificates. When the printed area is scratched or violated with a razor blade, black smudge marks appear. UV fluorescence can be added for additional security.

Desensitizing Inks—Spot-applied by wet sheetfed or web offset printing, these invisible inks deactivate selected areas of the coated front areas of carbonless papers, inhibiting the transfer of information from one ply to another in multi-part forms. Random patterns alert document readers of deviations or alterations.

[For details on an entirely different type of invisible ink, read the second part of this two-part series in the September issue of GAM.]