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Card marking is the process of altering playing cards in a method only apparent to marker or conspirator. This allows different methods for card sharps to cheat or may be used for magic tricks. To be effective, the distinguishing mark or marks must be done on the obverse side, which are normally uniform. Card marking can sometimes also be called as card bending; it is considered to be the easiest way to mark probably. A cheater marks a card by crimping here. Card marking is often used to cheat when gambling or for card tricks, though many casinos, particularly those in Las Vegas, punch holes through the middle of cards they sell to tourists to prevent cheaters from returning to the game tables after buying the cards and then slipping the favorable cards into their hands when playing.
Marked cards can be used regardless of who shuffles and deals the cards. However, some more sophisticated marked-cards scams involve additional manipulative skills to steer the cards into the correct positions once the desired cards have been identified.
Historically, the first attempts to mark playing cards involved bends, crimps and tiny bumps, which are called blisters (and resemble the Braille script). Later, when the first designs appeared on the backs of playing cards, cheats began altering the designs on the backs of cards. Hustlers have tried using various inks, pigments, scratches, etc., to add or remove lines or patterns from the back of the card design. Some varieties of card marking include block-out work, cut-out work, scroll work, shade work, tint work, etc. Here is a simple example of how block-out works and die in a hole cup. [clarification needed]
However, more recently, science and technology have also enhanced marked-card techniques. The most state-of-the-art technologies are variations of shade techniques.[clarification needed] These new technologies are the most deceptive and futuristic methods for marking cards. Traditional block-out and/or cut-out work[clarification needed] have the disadvantage that they must be read close-up, because the marks are small. On the other hand, another advantage of luminous and juice marked-card technology[clarification needed] is that they can be read close-up or from across a table.
Detecting marked cards
1) Perform the gamblers' riffle test (also known as "going to the movies"). This test allegedly allows a person to detect most marked decks by simply riffling the cards. Looking at the back of the cards while they are being riffled, the marks will allegedly dance around the back of the cards like an old-fashioned cartoon. In fact, one must know exactly what marks to look for, or this method of detection may not work. The riffle test is less effective for detecting cards marked with luminous and juice.
2) Reflect light off the back of the card. Cut-out work (scratches or white ink) will display, as well as many inks or solutions that tend to dull the finish on playing cards because they are alcohol-based. Only the highest quality solutions will not burn the finish of cards. Placing a drop of alcohol on a card and then looking at the finish by reflecting light off the back reveals the dulling effect that these cheap solutions can cause.
Block-out and cut-out work
- In brief, block-out work is simply using the same color ink as the back of the card and coloring in small white areas of the card. For example, sometimes people add ink to the flowers on the back of a card by making the petals narrower or blocking out a bird on the back design.
- As far as cut-out work is concerned, people sometimes use a razor to scrap off some of the printed areas of the card. A good example would be to use a razor to scrape off the print on the card. This results in adding (cutting out) a white bird to the back design.
- Luminous marked cards - These can only be read by using special gimmicked sunglasses or by wearing contact lenses. The original luminous systems used red lenses and greenish ink on the back of red cards. New luminous technology, called Ultra-Luminous, uses far more sophisticated techniques that are based upon chemical and optical scientific principles different from the original luminous systems.
- Video-luminous marked cards - As stated above, luminous marked cards are designed to be read by the human eye with the use of filtered sunglasses. However, recently, a new generation of luminous technology has become available. Video-luminous uses marks that can not be seen by any human being, even if they are looking through a luminous filter. The marks can only be read by using custom-designed electronics and filters and displayed on a TV monitor in another room to a partner. Then the card values may be signaled or transmitted to the player who needs to know.
Video-luminous does not have to be used for cheating. They may be used for magic or by a poker house or person who may want to analyze a card game after the fact. If collusion is suspected, the recorded images of the marked cards may be played back later to detect any unusual play. If a player consistently folds a good hand when a partner plays a better hand, then it can be assumed that collusion is taking place in the game. Since these marks cannot be seen by the human eye, there is no chance of detection of the marks, even by knowledgeable players, during the game. Often such marked decks will only be introduced by the house when suspected colluders are seated.
- Juice-marked cards - The marks are only visible when a person is trained to read the marks (no filtered sunglasses are required, but some practice is required to read the marks). Glasses can be used to make it easier to spot these marks.
- Tintwork or shade - This technique uses a tint solution to mark cards, but the marking patterns vary depending upon the back design of the cards being marked.
- Daub - A special paste is used by a player to mark someone else's deck, on the fly, while the cards are being used during a game and even while being watched. This eliminates the need to switch in a pre-marked deck of cards.
- Juice dust - An advanced type of daub, it may be used to make an ad-hoc juiced deck. Like daub, it also allows a player to mark someone else's deck, on the fly, while being watched. The main advantages of juice dust are that it will not dull the finish of the cards and that it works on both paper and 100% plastic playing cards.[clarification needed]
It is not necessary to mark the entire deck in order to gain an advantage in most types of poker - even marking just one rank (especially the aces) is enough to gain a significant advantage in a game such as Texas hold 'em.
- "Card bending at Blackjack". BlackjackCheating.com. Retrieved 2010-05-01.
- "Guide to Professionally Marking Your Playing Cards".