Marked decks: types and systems

A marked deck, also called a deck of “readers,” carries a hidden code on the backs that tells you each card’s value and suit. The published types are printed readers, block-out, cut-out, tint or “juice” work, luminous marks seen through tinted lenses, and marks added during play. Magicians use them for mind-reading and card location. Using one in a real game is cheating, and it can be a crime.

Why would a magician want to read the backs?

Imagine knowing what card someone is holding without ever seeing its face. That one piece of knowledge turns into mind reading, predictions, and finding a card that has been lost in a shuffled deck. It’s why the marked deck appears in our guide to trick decks and which to buy first as the natural choice for anyone drawn to mentalism.

It is also one of the oldest tools in card trickery, and it came from the gambling table first. The best way to understand it is through the old books that exposed cheats, which are still in print as free ebooks.

What is a marked deck?

S. W. Erdnase put it simply in The Expert at the Card Table (1902): marked cards, “generally known as ‘readers,’” can be distinguished by the backs “as readily as by the faces when the key is known.”

John Nevil Maskelyne, in Sharps and Flats (1894), wrote that “The systems of card-marking are as numerous as they are ingenious.” He sorted them under two principles: either each card gets its own distinctive mark, or every card gets the same mark and its position tells you the card. Both writers noted that a mark at one end of a card has to be repeated at the other end, so the card can be read whichever way round it is.

Both men wrote to expose cheats, not to train them. Marked decks sold for magic are made for performance. Using one to win money at cards is cheating, and it can be a crime.

How do the main types of marking work?

We’ll stay at the level of the published categories. Every commercial deck has its own system, and those are the makers’ secrets.

• Printed readers. The code is built into the back design when the deck is printed. Erdnase noted that printed marked cards existed in his day but were rarely used by professional cheats, because their designs didn’t match the standard decks on the table. For magicians, that problem matters far less.
• Block-out. Small white areas of the back design are filled in with ink of the same colour, so a petal or a dot quietly disappears. Erdnase uses the word “blockouts” for this kind of mark.
• Cut-out. The reverse: a tiny bit of printed ink is scraped away to leave a white spot that wasn’t there before.
• Tint, shade and juice. A faint wash of colour close to the card’s own colour is applied to part of the back. Maskelyne described shaded cards that could be told apart at two or three yards, adding that “the closer one looks at the cards the less likely one is to discover the mark.” Modern “juice” decks work on the same family of idea and are read by a trained eye without any glasses.
• Luminous readers. The marks are meant to be seen only through tinted lenses or filters.
• Marks added during play. Robert-Houdin’s Card-Sharpers: Their Tricks Exposed (1863) has chapters on pricked cards, cards with marked edges and bent corners. Erdnase describes cheats creasing or indenting cards with a fingernail during a game.

Maskelyne also retells a story from Robert-Houdin about cards seized from a cheat that looked perfect for weeks, until a pack thrown across a table caught the light and showed a small unglazed spot on each back. It’s a good reminder that the mark is often about light and angle, not ink.

When should you use a marked deck?

• Mind reading. A spectator looks at a card and you name it, or you sense which of several cards they are thinking of.
• Location. A card goes back into the deck, gets shuffled, and you find it by reading the backs as you spread through.
• Prediction checks. You know what has been dealt or chosen before the reveal, so you can steer the ending.
• As a quiet backup. With a marked deck in play you always know a card, whatever trick you are doing, which can rescue a trick that goes wrong.

How do you learn to read one?

Be honest with yourself about the work. Learning the key takes an evening. Reading it at a glance, in bad light, while talking to someone, takes much longer.

1. Learn the key cold. Values first, then suits.
2. Drill with a timer. Deal cards face down and name them, then check. Speed comes after accuracy.
3. Read without looking. Practise taking in the mark while your eyes and attention seem to be elsewhere.
4. Build presentation. Knowing the card is the method, not the trick. Our post on one-way decks covers a related principle you can combine with it.

Which products help?

• Sharps and Flats by John Nevil Maskelyne is a free public-domain ebook in our library: a complete exposé of the card sharp’s methods, including marked cards.
• Marked Deck (Blue Bee Style, Juice) by David Malek is marked with a juice formula and comes with full instructions. Its description says it can take anywhere from an hour to a week to learn to see the markings, and that the deck is not intended for gambling.
• Red Roses Gold Foil Playing Cards (Fully Marked) has fully marked reader backs hidden in floral artwork, plus a double backer, an unmarked 2 of Diamonds duplicate and one-way faces.

What are the common mistakes?

• Staring at the backs. The moment you study a card, people start studying it too.
• Being too fast and too perfect. Naming a card instantly looks like a trick. A pause and a struggle look like mind reading.
• Hinting at the method. Never joke about marked cards while using one.
• Bringing it to a game. A marked deck belongs in a performance, never at a card table where money is at stake.
• Losing the deck. Don’t leave it lying around for curious hands after the show.

Frequently asked questions