GGB is committed to providing updated news and analysis on our weekly news site,


The resurgence of marked cards


According to the Chinese, 2013 was the year of the snake. From a game protection perspective you could have called it the year of marked cards.

An unusually high number of cheating cases involving marked cards hit the news last year. Among them was the arrest of high-profile Las Vegas gambler Archie Karas. Another player was arrested in two states and labeled a “serial card cheater” by the media. Two dealers in a major East Coast casino were accused and charged of marking cards for players on a baccarat game.

So are we on the verge of a card-marking zombie apocalypse or should we ignore the whole thing like the Korean guy who sang “Gangnam Style?”

Before I offer my take on this, let’s start with a little perspective. 1) Card marking isn’t new. If there were a Mount Rushmore of cheating techniques, it would be Abraham Lincoln. It’s always been a threat in table games, and until we make table games digital, it always will. 2) There are a gazillion ways to mark cards. However, recently some cool stuff has emerged. New technologies are allowing cheats to run wild with their imagination. 3) Card marking is not hard to detect—if your staff pay attention.

Card Marking Isn’t New

There is a lot of information out there on how to mark cards. A lot of it is written for Chris Angel wannabes—bored college students and wise guys who like to cheat their friends in private poker games. In a casino environment it’s a little tougher to get away with it, regardless of how easy the authors of such information may imply that it is. However, indications are that it may be getting easier.

In casino land, it is not uncommon to see players marking cards using the most simple of techniques. They’re embarrassingly low-tech: card bending, nicking, scratching, knuckling and fingernailing. All names that are self-explanatory.

One of my favorite card-marking moves is the chip indent. It’s a great way to mark cards on games where players are not permitted to touch the cards. The cheat simply uses his chips to mark cards. The move usually takes place during the dealer’s “take and pay” procedures.

While the dealer is engaged in the payout process, the cheat, under the premise of placing the chip as a wager for the next hand, will take the edge of his chip, lean forward and place an indent on the target card as it lays face-up on the table. Cheats have also been known to use this technique under the premise that they are giving the chip to the dealer as a tip. I’m guessing any suspicion by the dealer of foul play was quickly overcome by the gratuitous gesture from the player.

I remember my first card-marking observation in surveillance. It was a guy playing double-deck blackjack. He was sticking his fingers in his ears and using earwax to mark the backs of 10s and aces. Moral of that delightful story: throw away the books. Cheats don’t play by the book.

Chemicals and Concoctions

That brings me to “substance abuse.” Although earwax and other bodily fluids are readily available and accommodating to the low-budget low-life, they’re not as sexy as chemical substances and the so-called invisible inks. An online cottage industry has sprung up over the last few years where anyone can buy chemical substances that can be used for marking cards.

The most common substance is daub. Mainly used by magicians, it’s a substance that can be smudged on a card that allows only the trained eye to see. It is not invisible, but it is very difficult to detect unless you know what you’re looking for. You can buy the stuff online for around $50. Most vendors suggest that their products should be used for entertainment purposes only. I guess gambling is entertainment.

If you want to step up to the sports car of card-marking systems, try the new high-tech invisible inks. The word ink is a little misleading. These are substances that are concocted by guys that like to blow things up. This stuff is going for big bucks. I’m talking hundreds, even thousands. Vendors use cool names to market their magic concoctions but give very little detail on what the stuff actually is.

Regardless of whatever the stuff is, it works. It’s undetectable to the human eye unless you view it through a special lens.

In the old days, the most common invisible ink marking systems were ultraviolet (UV)-based. UV chemicals were used that could only be viewed with UV lenses or lights. You could spot those guys a mile away. They were the ones with the rose-tinted sunglasses who should have been arrested by the fashion police. To combat the threat, we went out and bought UV black lights and introduced them into our card inspection processes. If we suspected someone was marking cards, we simply waved the light over them and the cheat was busted. It didn’t take long for cheats using UV marking systems to give up the caper once they knew we had the equipment to detect the markings.

But that was so ’80s and ’90s. Nowadays, cheats are exploring new high-tech card marking systems. The method that is hot right now is infrared (IR) card marking. Without getting too scientific, IR basically works better because a UV light will not detect the markings. Casinos should not make the mistake of relying on UV lights only to detect marked cards these days. Cheats will take advantage quicker than management can say, “You can’t touch this.”

Infrared substances cannot be seen with the invisible eye, a UV black light or a standard surveillance camera. IR chemicals can be purchased that can only be seen at 900 nanometers on the visible light spectrum. This makes detection almost impossible. To see the markings, a player has to use a special IR lens usually fitted in a pair of glasses or contact lens. Often they look like designer glasses and don’t draw as much negative attention from fashion police. The contact lenses used to identify the markings look just like normal contact lenses. Don’t expect a cheat using IR contact lenses to look like Michael Jackson in the “Thriller” video.

What’s In It for the Cheat?

So, why do cheats mark cards? What is the return on the risk? Lets face it, marking cards doesn’t guarantee the cheat will win; however, it does offer inside information that can lead to a pretty sizable advantage if betting and playing strategies are adjusted to exploit the information. There are three reasons a cheat marks cards: 1) to gain knowledge of the first card out of the shoe for determining bet size; 2) hole card knowledge; and, 3) next-card knowledge for hit and stand decisions.

Here are some of the ways cheats can gain an advantage by marking valuable cards on some of our more popular games:

Baccarat: Mark the high cards Six through Nine. If the first card out of the shoe can be identified as a high card—bet the Player. If it’s a low card—bet the Banker. A player’s overall advantage if they bet this way for the entire shoe is almost 7 percent. Alternatively, to save time but still gain a reasonable advantage, just mark the Eights and Nines.

Blackjack: Mark the Aces and Tens. Sit on the first box to allow you to get the first card out of the shoe. Whenever it’s a 10 you have about a 13 percent edge over the dealer. If it’s an Ace, you have a whopping 52 percent edge over the dealer. Hole card and hit/stand knowledge can also be exploited to gain an edge.

Mississippi Stud Poker: Mark the Jacks. A player can gain an edge of about 38 percent if they adjust their playing strategy.

Three Card Poker: Mark the Aces, Kings and Queens. A player can gain an edge up to16 percent if they adjust their playing strategy.

Caribbean Stud Poker: Mark the Aces and Kings. A Player can gain an edge of about 7 percent if they adjust their playing strategy.

Scary New Technology

Right now there is some scary technology coming out of China that incorporates IR marked cards, concealed cameras and computer analyzers. Combined to create a high-tech card marking system, I must say that this device could do for cheats what silicon did for the cosmetic surgery business. The devices are being marketed as poker analyzers.

The technology works like this. The long edge of every card in the deck is marked with an invisible IR marking. Each mark identifies an individual card. In collusion with a poker dealer, the special marked deck is swapped into play. The player sits opposite the dealer on the table. He positions a concealed camera on the table (usually disguised as a cell phone). The camera has an IR lens that is used to transmit an image of the edge of the deck of cards to a small computer located in a smart phone (the poker analyzer) in his pocket. The image is transmitted during the period after the dealer has shuffled the cards and the deck is resting in front of the dealer before cards are dealt to the players. The IR snapshot of the cards looks like a barcode. The poker analyzer identifies every card in the order that they will be dealt to the players in less than a second. A computer-generated voice message is sent to the player via a Bluetooth mini earpiece communicating the rankings of all the hands on the table.

The device is constantly being improved to cover a variety of games, to be even more easily concealed and to increase the range of the distance the camera can be away from the cards.

The hard part of pulling the scam off is recruiting the dealer. Not really. Nowadays, employee collusion in casinos is as common as car insurance commercials on TV—a sad byproduct of the reduction of supervisor levels on the floor and an ethos of literally giving the gambler whatever they want.

The question we have to ask ourselves is, could this technology and card-marking system be used to cheat in other table games we offer, like baccarat and blackjack? I say yes. Recruit the dealer and control the table. The capabilities to beat other card games in the casino are only limited by software design.

Time for an Eye Test

Here’s my take. Last year we caught a few cheats who arguably weren’t the sharpest tools in the shed. They got busted using chemicals to mark cards. I suspect they were like kids with new toys. The good thing is they brought attention to the development of new cheating technologies that should be taken seriously by game protection professionals around the world.

Generally over the years, the casino industry has been able to keep a reasonably tight lid on card marking. Dealers, floor supervisors and pit managers used to be trained to be vigilant and on the lookout for indications players were marking cards. Reductions in floor supervisor levels, a lack of proper job-specific specialized training and a generally lower management emphasis on game protection are arguably providing more opportunities for organized cheats.

Moving forward, I suggest a casino’s strategy for combating the threat of card marking should include a two-pronged attack combining an old-school and new-school approach.

Old-school approach: Train all staff in table games and surveillance to recognize the “tells” of a card marker. Watch player’s hands, in particular their fingers. The same goes for dealers. Let’s not forget that dealers have the ability to mark cards and collude with players. Watch the betting strategies of players. Are they betting in correlation with a first-card advantage? Do they appear to be playing with hole-card knowledge? Are they varying from basic strategy on blackjack? These are all indications that marked cards may be in play.

New-school approach: Surveillance, this one’s for you. If you suspect someone is marking cards, it’s time to fight fire with fire and bring in a little technology of your own. Put your black light back in your holster for a moment and consider this. Most surveillance cameras, in their natural state, actually have infrared viewing capabilities. The problem is the picture is not so good, so manufacturers add a cut filter over the CCD chip to block out infrared light.

The good news is the cut filter can be removed to convert it into an IR camera. A number of major surveillance camera systems provide end users the ability to remotely change the IR status of the camera via the operator’s keyboard. This allows the operator who suspects someone is marking cards at a table to use a PTZ camera assigned to the table to switch to IR mode so the cards can be checked live on the game. If you currently don’t have this feature, speak to your manufacturer.

Final Thoughts

I’ve heard of cheats using radioactive chemicals to mark cards. What next—DNA? As some experts have told me, there’s no one method of detecting all the possible chemicals that could be used. This is why in my opinion, the old-school approach of paying attention to how the game is being played should be first and foremost in any game protection strategy to combat marked cards.

In saying that, like organized cheats, we should be proactive in exploring new technology opportunities. When you look at the development of products like Google Glass, it isn’t hard to imagine that one day we may all be wearing contact lenses to help process information more quickly and accurately. The key to many emerging analytic technologies will be cameras and lenses. The ability for computers to analyze images from video to provide useful information is exciting.

Smart camera technology could be a game-changer. Mark my words.

Willy Allison is a game protection consultant/trainer and the founder and managing director of the World Game Protection Conference in Las Vegas. He started in the casino business in 1987 and has worked in surveillance management, consulted for major casino organizations and conducted game protection training seminars around the world.

    Recent Feature Articles

  • Funding the Future

    Gary Ellis’ vision of a cashless casino ecosystem with Marker Trax and Koin

  • Age of the ETG

    Electronic table games have grown from simple automated roulette machines into a genre that is steeped in innovation.

  • Online in Ontario

    Stakeholders deem Ontario a success, but also a work in progress.

  • Mixing It Up

    Developing slot floor strategies for emerging markets.

  • Gaming & Diversity: Staying the Course

    DEI has encountered big resistance of late. Here’s how gaming companies continue to build a fairer workplace.