Card marking technology is the way card sharps and magicians mark playing cards for cheating or magic tricks. It is also the way in which those marked cards can be detected by poker analyzers and other equipment used for gambling card game protection.
Hustlers use a variety of methods to mark cards, from simple bends and crimps to more elaborate alteration of the card-back design. The earliest forms of card marking involved adding small, invisible markings or stains to the backs of the cards. These markings, called “blisters”, resemble the Braille script and were used to identify the rank of a particular card. Later, abrasions and inks were used to add or remove lines, shapes and other designs on the card backs.
More recently, card marking has become more sophisticated and complex, with the introduction of different types of marker inks and paints that can be hidden on the face of a deck of cards. These inks are mixed with color to match the specific background or pattern on a card. This makes the inks almost imperceptible to the naked eye, but detectable by a special poker scanner or analyzer.
There are several ways of marking cards, including block-out work, cut-out work, tinting and shade work. Block-out work involves cutting out certain parts of a card back pattern with a razor blade or craft knife. Tinting is a subtler variation of this, with the smearing of a light ink on specific parts of a card back pattern. For example, the head of a card would be subtly tinted while the left wing of an ace or the heart of a queen would be lightly colored in.
A simpler method of card marking is daubing, where a card sharp or con artist will smudge the back of a playing card with an indicative speck of ash or dirt while the card is in play. The simplest card marking techniques, daubing requires advance access to the deck of cards, but more advanced methods have allowed players to mark other players’ decks on-the-fly during a game without any prior knowledge or preparation.
Another type of card marking, luminous cards, are made with invisible inks and can only be seen by those who know how to read them. These marks are often recognizable as variations in patterns, color or shade and can only be seen by those wearing special sunglasses or lenses designed to detect them. More advanced luminous cards, such as ultra-luminous or N-Dust cards, are only detectable with cameras and other specialized gadgets. In any case, even if a person knows how to read luminous markers, it is impossible to hide them from poker scanners or other devices that can detect invisible ink. That is why poker players must be aware of the dangers and learn to watch for tells that indicate a player is using marked cards. This will help them avoid getting ripped off by unscrupulous con artists and card cheats.