To avoid being detected by other players or dealers, card marking is an art that must be mastered. Some marks are easily detected, while others can only by seen with special eyes that have trained to see them. This kind of marked cards are typically used for cheating at card games, but it’s also used by magicians as part of their tricks.
This ink can only be seen by those who are trained to read it. This ink is applied to the back of a card in a specific spot that isn’t visible to a naked eye, but can be viewed with special contact lenses or filtered sunglasses. There are many different types of inks available for marking cards, but luminous ink that is invisible to the naked eye is the best.
Block-out marks, tinting and daubing are other ways of marking cards. Block-out marks are small and can be detected by a careful riffle test or by the gambler’s eye, but this method does allow for more complex reversal of the card values. Tinting is a similar method to block-out, but instead of coloring all the card, it uses a tinting agent.
Daubing can be a very interesting technique because it occurs during the game, and even while the card is played. One player can apply a special paste to the back of a playing card on the fly. This can be used as a signal to reverse the card values in a game. This is useful for poker and magic shows, as it eliminates the need to bring a deck of cards that have been pre-marked into a game.