Part I: Card Game Cheating · CARD MARKING METHODS

Pin Pricking / Blisters

How it works

Pin pricking involves using a sharp pin or needle to create tiny raised bumps (called “blisters”) on the surface of the card. These bumps can be felt by the cheater’s fingertips and resemble Braille script. Different patterns and positions of blisters indicate different card values. This technique is completely invisible to the eye and can only be detected by touch. The cheater reads the marks while handling or dealing the cards.

Where it appears

Poker, Blackjack, any card game

On the record

Pin pricking is one of the oldest marking methods, predating printed card backs. It was widely used in the 18th and 19th centuries and remains effective today because it requires no visual reading.

Published as a detection reference for surveillance, compliance and gaming-operations professionals. Thresholds and tuning are set by the property. Nothing here is instruction — the method is described so it can be recognised.