Unfair Dice

Loads, Gaffes, Sliders and Other Polyhedral Perils

by MXSavant

In a previous article (Diddling With Dice) I discussed some probability theory and how one might think more clearly about what the dice are likely to do in a particular situation. You may recall that I used the term “fair six-sided dice” and made passing reference to loaded dice. Well, today we are going to explore the sleazy underbelly of those pesky little polyhedra that can spell victory or disaster on the gaming table.

Loaded dice are as old as the history of gaming. Loaded dice have been found in Egyptian tombs, among the remains of Roman civilization, and in many other places. Records of dice games are found ancient Indian texts from around 1,500 BC, where the stakes could go as high as possession of a kingdom along with hundreds of slave girls. As you might expect, the dice in this particular contest were loaded. In Fifteenth Century England, a certain gentleman and scholar named Roger Ascham, published a catalogued of loaded and gaffed dice when he wasn’t working as a professor of Greek at Cambridge or as a tutor to Elizabeth I.

So, it may not surprise you to learn that one can order loaded versions of the polyhedral dice so familiar to us gamers. They are available from several sites on the Web. You can not only buy loaded dice, but unspotted dice that would be easy to turn into mispots (see below). Commercially available unfair dice is a subject for another time; let’s get down to particulars.1

Dice that have been modified in order to create a less random outcome are called “loaded” or “gaffed” dice. Most people know about adding weights to dice to make them unbalanced and more likely to land with a certain face up (see Figure 1).

Loading a D6 with small metal slugs.
Photo from A. D. Livingston, Dealing with
Cheats. Illustrated Methods of Cardsharps,
Dice Hustlers and Other Gambling
, 1973.

But these sorts of loads are only a small fraction of the many ways one can create unfair dice. A die can also have an air pocket hollowed out, which can also unbalance a die. These kinds of dice are called “floaters” because they often will float in water where a fair die would sink, although not all “floaters” will actually float. Dice with indented pips will have a very slight imbalance due to the amount of material removed to make the pips, which is why most casino dice have spots that are printed on and not indented. Casino dice are also highly precise and are true to tolerances as fine as one fifty thousandth of an inch.

The kind of gaffe used will depend on what the dice hustler wants. Some dice are designed to win (called “passers”) or lose (called “missouts”). These dice are switched in and out of a game by so-called “switchmen” or “bustout men”. Other dice are intended to be left in play and used over many throws in a game. They are gaffed simply to give a slightly better percentage of rolling favorably. These “percentage” dice can be the result of deliberate modification, or simply a product of poor manufacture. Here are some other common methods of gaffing dice:

Mispots. Also called top-and-bottoms, horses, tees, tops, or busters. Mis-spotted dice seem like a very obvious ploy, but on a D6, consider that you can only see three spots at any one time.

Flats. A die that has been shaved down on one side will have slightly more surface area on that side and consequently will have a higher chance of landing on that side. Shaving off just ten to fifty thousandths of an inch is enough to make a difference. Different sides of a die can be shaved if there is more than one acceptable outcome. It is also allegedly possible to bias a die by squeezing it in a vice equipped with soft copper jaws.

Bevels. These dice have one or more sides rounded just a bit, which causes the dice to roll off the beveled side and come to rest on the flat sides. One can even combine flats and bevels on the same die.

Suction Dice. These have one or more of the surfaces shaved to a very slight concave shape. This creates a suction effect that can cause a die to come to rest more often on the concave side.

Edge-work dice. You can change the size of a flat side of a die by changing the angle of the edge where two sides come together. Carefully shaving that edge can reduce or enlarge one side, on which the die will be more likely to come to rest. One can also roughen the edge of a die with sandpaper or some other tool. The rough edges can catch in the fibers of a cloth-covered surface and cause the die to flip over onto a particular side. Another variation called a “pig-bristle die” inserted a tiny bristle in an edge to catch on the playing surface.

Painted dice. Some solutions can be applied to one side of a die to make it stickier. The more sophisticated gaffer will use solutions that don’t become tacky until they are warmed by a player’s hands. Another trick is to apply a clear resilient material that makes dice bounce off of one side. Dice treated in this way are called “caps”. Even good old fashioned honey has been used to make dice sticky, but this wears off after a few throws.

Burr dice are made by drilling into a die spot, and when the drill bit is removed, a small burr remains. This burr can catch in the fibers of a felt game table and cause the dice to tumble over in a favored way. Sometimes burrs are the byproduct of sloppy manufacturing.

Rough dice. Dice that have been slightly abraded with sandpaper or some other abrasive on one side are more likely to tumble off that side and come to rest on a slicker side.

Slick dice. By contrast, slick dice have one or more highly polished side. Slick dice are more likely to come to rest on one of the slick sides.

This is by no means all of the many ways dice can be gaffed, but they are the most likely to be encountered in a gaming situation.

In addition to gaffing the dice, there are people who have made a science of manipulating dice as they throw them. These “slickers”, as they are called at the craps tables, can do amazing feats of sleight of hand and exercise a surprising amount of control over how the dice fall. Two ways to defeat slickers is to use a dice cup (a precaution suggested by Aristotle), and insist that dice strike a vertical surface before coming to rest. Be sure your dice cup has an inner lip around the edge to prevent certain kinds of trick throws. An even better way to stop slickers is to use a dice tower, which we will discuss in another article. My own experience is that true dice mechanics don’t show up at wargaming tables much, probably because there’s no money being wagered.

In a future article, I’ll clue you in to how to spot gaffed dice and suggest precautions to keep the dice at your gaming table or convention honest.

1. Much of the material for this article is taken from A. D. Livingston, Dealing with Cheats. Illustrated Methods of Cardsharps, Dice Hustlers and Other Gambling Swindlers. J. B. Lippencott Co., 1973. See especially Chapter 13, “Craps”. Additional material was found on Answers.com at http://www.answers.com/topic/dice.