There are many ways to mark cards to give cheaters and hustlers an advantage in gambling or card tricks. The markings on cards can be as subtle as coloring in or scratching away parts of a deck, or they could involve tinting. Some markings are invisible and require special glasses, but others can be detected using the riffle-test.
Traditionally the simplest way to mark a deck of cards is to apply pre-prepared marks to a deck before it is used in game. It can be done in many different ways, with some systems requiring high levels of skill. This is the reason why hustlers, cheaters and con artists spend so much practice and time perfecting these techniques.
One of the more common methods is to mark a deck of cards with ink that is a shade darker or lighter than the original card stock. This technique can be used in many different ways, including block-outs where the design of the card is blocked out using ink that matches the card stock’s shade and cut-outs where white areas such as birds or flowers are scraped away with razors or other sharp tools.
Some of the more advanced card marking systems use luminous markers which can be read by special sunglasses or contact lenses. These are usually more difficult for players to use, as they will need additional manipulative skills in order to ensure that other players cannot see the luminous markers.
There is also a newer method of card marking that uses a chemical called juice dust to mark cards on the fly. This is a variation of the daub technique that can be used to alter cards without the gamblers realizing it. The strength of the marks is dependent on the cheaters’ skill and the ability of honest players to read patterns of blotches.
