“Mark of Integrity”, 2009-02 (; similar):
[Card marking is a venerable and sophisticated art. Jonathan Allen on juiced cards, luminous readers, sunning the deck, and other sharpers’ tricks (card marking)]
The history of the marked playing card, perhaps as old as the playing card itself, is a miscellany of inventive guile. “The systems of card-marking are as numerous as they are ingenious”, wrote John Nevil Maskelyne in 1894. “Card doctoring”, to use Erdnase’s term, covers many forms of subterfuge, but in the brief survey that follows, we shall focus our attention upon what might more usefully be termed the “language” of the marked card.
…“Luminous readers” are cards treated in such a way that pale green ink traces become clearly visible when viewed through red-filtered spectacles or contact lenses. The technology caused alarm upon its discovery but, due to its limited effectiveness and its reliance upon somewhat vampiric eye adornment, has remained more of a popular novelty than a serious subterfuge.11
“Juiced cards”, on the other hand, do not need lens-based viewing, instead requiring the reader to defocus his or her eyes and spot liminal fluid-residue marks on an opponent’s distant cards (juiced cards are also known as “distance readers”). To many players, juicing, and its recent high-tech offshoot, “video juicing”, are the most effective real-world card-marking system available, and the considerable price of the closely guarded fluid recipe and application technique reflects this growing reputation.
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