Question: What Is Glass Analysis?

Glass analysis includes determining the type of glass based on glass fragments.

Basic properties, such as color, thickness, and curvature, can also help to identify different samples of glass just by looking at them.

Optical properties, such as refractive index (RI), are defined by various manufacturing methods.

What is glass analysis in forensic science?

The aim of forensic glass analysis is to recognize the origin of the glass and to determine if a glass fragment is associated to the crime scene. The analysis is based mostly on the examination Page 2 of physical and optical properties of glass, such as: color, thickness, density or RI.

What is the forensic significance of glass?

Broken glass is often found at crime scenes and can be used as forensic evidence. This lesson is about the purpose of collecting glass as forensic evidence, the collection process, and its preservation.

What is glass evidence?

Windows, automobile glass, broken bottles, and other glass objects may be crucial evidence in burglary, murder, hit-and-run and many other types of crime. The Physical Evidence Bulletin is a guideline intended for law enforcement agencies for the collection and submission of evidence to BFS Laboratories.

How can you tell which side of a glass is broken?

Be sure you know which is the inside (or outside!) and look at the glass from the side. The force of the bullet hitting one side will break away a crater on the opposite side of the glass. The glass is tapered, from the impact surface away to a larger hope on the side opposite the impact.

How Can glass be used as evidence?

Glass – Glass can be used to gather evidence, for example collecting fingerprints or blood from a broken window; however, glass also has a place in the trace evidence section. Broken glass fragments can be very small and lodge in shoes, clothing, hair or skin.

What are the two types of glass fractures?

The radiating lines are appropriately known as radial fractures, and the circular lines are termed concentric fractures. Radial Fracture – A crack in a gloss that extends outward like the spoke of a wheel from the point at which the glass was struck. Concentric Fracture – A crack in a glass that forms a rough circle.

What are the two most often used methods of glass analysis?

Most crime scene glass originates in windows, automobile headlights or containers. Forensic scientists know that glass fractures in two basic patterns–radial fractures and concentric fractures. If an object like a rock is thrown at a window the window will fracture first in a radial pattern.

What are the two class characteristics of glass?

  • Class characteristics: physical and chemical.
  • properties such as. refractive index, density,
  • color, chemical composition. Individual characteristics: if.
  • the fragments can fit. together like pieces of a.
  • puzzle, the source can be. considered unique.

What is the main ingredient in glass?

Main glass ingredients: sand / soda / limestone. 70% Silica (sand) SiO2 , 18% Sodium oxide (soda ash) Na2O, 12% Calcium carbonate (lime) CaO melted at around 1320 degrees Celsius makes a typical glass which can be formed by blowing by mouth or machine, by casting, by pressing and by drawing.

What are the types of glass?

The types of glass used in construction are: Float glass. Shatterproof glass. Laminated glass.

  1. Float Glass.
  2. Shatterproof Glass.
  3. Laminated Glass.
  4. Extra Clean Glass.
  5. Chromatic Glass.
  6. Tinted Glass.
  7. Toughened Glass.
  8. Glass Blocks.

What chemicals are used to make glass?

Ingredients. Silicon dioxide (SiO2) is a common fundamental constituent of glass. In nature, vitrification of quartz occurs when lightning strikes sand, forming hollow, branching rootlike structures called fulgurites. Fused quartz is a glass made from chemically-pure silica.

How do you collect evidence from glass?

Place small glass fragments in folded paper packages, and then in envelopes. Seal and mark. Place large glass fragments in bags or boxes but separate individual pieces with newspaper to prevent breakage and damage to edges. Complete the evidence tag and attach it to the packaging.

What is commonly the first step in glass analysis?

Direction of force determinations: This method determines which direction a projectile went through the glass by evaluating radial fractures in the glass fracture’s first concentric ring. The first step in this method is to find radial fractures that are within the first concentric fracture.

What happens when a bullet hits glass?

A bullet fired from inside the same car would easily pass through the glass because the bullet’s force is concentrated on a small area, which causes the material to flex. This causes the brittle material to break outwards, allowing the bullet to pierce the flexible material and strike its target.

What are stress marks in glass?

Stress marks, seen on a cross section of a glass fracture, are shaped like arches that are perpendicular to one glass surface and curved nearly parallel to the opposite surface. The importance of stress marks stems from the observation that the perpendicular edge always faces the surface on which the crack originated.