Using marked playing cards is one of the most deceptive ways to cheat in poker. It’s hard to see and usually only works if there is a rigged game against one player. It’s possible to make a living if it’s done right.
Marked playing cards have markings on the backs of their decks that indicate their suit and value. You can also use these markings to tell which card has been dealt or the suit of a particular hand.
This type of marking can be done by adding a small amount special dye to the back of a printed card. You can use anything from a small amount of ink to paint to a chemical that reacts only to a certain light wavelength.
Although it isn’t as popular as juice and luminous methods of cheating, it can be very effective in certain situations. This is especially true if the deck is not shuffled properly, which can give you an advantage when playing Texas hold’em or Omaha.
These types of cards are sometimes called “contact lenses” or “luminous ink” cards. The ink on these cards is not visible to most people. However special contact lenses and glasses with a filter that allows for the visibility of the markings are available.
The best way for you to identify these cards is to do the gamblers riffle test. This involves moving your thumb through the deck and looking closely at the backs to check if there are any changes in the marks. This test can be especially useful for identifying luminous marked card because the backs of these cards will look normal to most players even though they have been dyed.
A second technique for marking cards is called “shade.” This involves using a small amount aniline ink on the back of a card, to shade it slightly. The dye or ink is almost colorless, but it provides enough of a tint to gray the white areas.
Some cases have the markings printed on the front of the card using special ink that can easily be read with special lenses. These lenses will make the ink look like a thin, clear layer of paint that can be clearly seen through them.
A cheater can even place a daub or paint on the back of a deck, then bounce an invisible light source from the side of the card. The cheater can then see through his contact lens or slightly tinted glasses the daub and paint, making it impossible to see for any other player.
This technique of card-marking is an old one, but it has been more popular in recent times. It can be used for marking many different items, but it is most common in a poker deck.