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Stuff Every Fingerprint Scout Should Know: the Study Guide

Practice facts for the Fingerprinting merit badge. Not an official Scouting America credential. Grab a snack: this guide is the friendly version, with the answers explained and a groan-worthy joke waiting at the end of most cards.

Knowing Fingerprint Scout saves you money, time and the occasional embarrassment.

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Chapter 1: Principles and Documents

What do arch pattern ridges do?

Short answer: Enter one side, rise in the center, exit the other side

Arch ridges enter from one side, rise in the center forming an arc, and exit the other side.

Groan of the day: That arch really bridges the gap.

Sources: Fingerprint

What do loop pattern ridges do?

Short answer: Enter one side, curve, and exit on that same side

Loop ridges enter from one side, form a curve, and exit on that same side.

Groan of the day: That pattern really loops you in.

Sources: Fingerprint

What do whorl pattern ridges do?

Short answer: Form circularly around a central point

Whorl ridges form circularly around a central point on the finger.

Groan of the day: That pattern has a lot of spin.

Sources: Fingerprint

What is a latent print?

Short answer: A chance print invisible to the naked eye

A latent print is a chance recording of friction ridges, invisible to the naked eye.

Groan of the day: That print is hiding in plain sight.

Sources: Fingerprint

What is a patent print?

Short answer: A print viewable with the unaided eye

Patent prints are viewable with the unaided eye.

Groan of the day: That print is easy to see, no glasses needed.

Sources: Fingerprint

What is a plastic print?

Short answer: A print found on soft material like soap

Latent impressions found on soft material such as soap, cement, or plaster are called plastic prints.

Groan of the day: That print is soft on details.

Sources: Fingerprint

What is live scan?

Short answer: Recording friction ridges digitally on a glass plate

Friction ridges can be recorded digitally, usually on a glass plate, using live scan.

Groan of the day: Live scan is a real glass act.

Sources: Fingerprint

What is an exemplar print?

Short answer: A deliberately collected known print

Exemplar prints, or known prints, are deliberately collected from a subject.

Groan of the day: That print is an excellent example.

Sources: Fingerprint

What is adermatoglyphia?

Short answer: A rare condition with no fingerprints

Adermatoglyphia is a rare medical condition with no fingerprints.

Groan of the day: That condition leaves no trace.

Sources: Fingerprint

What is a fingerprint sensor?

Short answer: An electronic device that captures a fingerprint image

A fingerprint sensor captures a digital image of the fingerprint pattern.

Groan of the day: That sensor has a good feel for the job.

Sources: Fingerprint

What is a biometric template?

Short answer: A collection of extracted features used for matching

A live scan is processed to create a biometric template used for matching.

Groan of the day: That template is a real matchmaker.

Sources: Fingerprint

What is a bridge or crossover?

Short answer: A short ridge between two parallel ridges

A bridge is a short ridge that runs between two parallel ridges.

Groan of the day: That bridge really connects the dots.

Sources: Fingerprint

What is dactyloscopy?

Short answer: Fingerprint identification

Fingerprint identification is known as dactyloscopy, ridgeology, or hand print identification.

Groan of the day: Dactyloscopy is a real handful.

Sources: Fingerprint

What is ninhydrin used for?

Short answer: Developing latent fingerprints

Ninhydrin is a chemical used to develop latent fingerprints.

Groan of the day: Ninhydrin is a real developer.

Sources: Fingerprint

What is a friction ridge?

Short answer: A raised portion of the epidermis

Friction ridges are raised portions of the epidermis on digits, palms, and soles.

Groan of the day: Ridge to the top!

Sources: Fingerprint

The cheat sheet

The whole guide on one screen. Screenshot it, print it, stick it on the fridge.

  • Fingerprints are impressions left by the friction ridges of a human finger.
  • The scientific study of fingerprints is called dermatoglyphics or dactylography.
  • The three basic patterns of fingerprint ridges are the arch, loop, and whorl.
  • Arch ridges enter from one side, rise in the center forming an arc, and exit the other side.
  • Loop ridges enter from one side, form a curve, and exit on that same side.
  • Whorl ridges form circularly around a central point on the finger.
  • Ridge ending is one of the features of fingerprint ridges called minutiae.
  • A bifurcation is a single ridge dividing in two.
  • A delta is a Y-shaped ridge meeting.
  • The core is a circle in the ridge pattern.
  • A latent print is a chance recording of friction ridges, invisible to the naked eye.
  • Patent prints are viewable with the unaided eye.

Pop quiz

Think of your answer first, then peek.

  1. What is a fingerprint an impression of?
    • Friction ridges on a finger
    • Hair follicles on a hand
    • Sweat glands on a palm
    Show the answer

    Friction ridges on a finger. Fingerprints are impressions left by the friction ridges of a human finger.

  2. What is a latent print?
    • A print visible without help
    • A chance print invisible to the naked eye
    • A print made with ink on a card
    Show the answer

    A chance print invisible to the naked eye. A latent print is a chance recording of friction ridges, invisible to the naked eye.

  3. What is adermatoglyphia?
    • A type of fingerprint pattern
    • A tool for lifting prints
    • A rare condition with no fingerprints
    Show the answer

    A rare condition with no fingerprints. Adermatoglyphia is a rare medical condition with no fingerprints.

  4. What is a lake or ridge enclosure?
    • A ridge that bifurcates and reunites
    • A single small dot
    • A Y-shaped meeting
    Show the answer

    A ridge that bifurcates and reunites. A lake is a ridge that bifurcates and reunites shortly afterward.

  5. What do friction ridges help amplify?
    • Sound waves
    • Vibrations for texture perception
    • Body heat
    Show the answer

    Vibrations for texture perception. Ridges amplify vibrations that help transmit signals for fine texture perception.

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