frsc 302 midterm

soda glass

soda glass

most prevalent type of glass, windows/glass bottles

birefringence

the double refraction of light

silica glass

made of silicon

obsidian glass

volcanic glass

leaded glass

glass that contains lead oxide - crystal

laminated glass

sandwich between plastic

borosilicate glass

boron addition enables glass to withstand heat, cookware

electric and magnetic waves

what is light

3R rule

radial cracks give rib marks that make right angles on the reverse side of the force applied

plain, twill, satin

3 common weave patterns

mechanical, chemical, thermal, electrical, optical

5 properties of glass

amorphous solid, rigid liquid

glass is an _____ and _____

delustrants

some manufactured fibers have this added to dull their shininess

stem, leaf, stem

parts of a plant used for fiber

plants, animals, minerals

fibers come from

art forgery, burglars, hit and runs

3 main types of cases paint analysis is used for

nonconvertible

evaporates solvent to dry

convertible

needs a chemical reaction to dry

small, highly variable, easily transferable

3 features of trace evidence

anisotropic

optical properties that vary with the orientation of the incoming light and optical structure of the material

isotropic

• demonstrate the similar optical properties in all directions

  • They have only one or singular refractive index

  • Light passes through them at the same speed with no directional restrictions

documentary, demonstrative, testimonial, physical

4 types of evidence

resolution

the minimum distance 2 objects can be separated and still seen as 2 separate objects

type, length, contact

3 factors that affect the likelihood of transfer

cellulose, pectin, lignin, fats

plants and vegetable fibers are composed of these

has no extinction

what makes cotton unique?

wet spinning

polymers extruded in chemical bath that causes fiber to precipitate and solidify

melt spinning

melted polymer liquid is extruded then hardens as it cools

dry spinning

polymers that need to be dissolved in a volatile solvent which rapidly evaporates causing solidification after extrusion

cuticle, cortex, medulla

hair parts from outside to inside

human, dogs

imbricated examples

bats

coronal examples

cats

spinious

anagen

80% of hair in this growth phase

catagen

2% of hair in this transition phase

telogen

20% of hair in resting phase for follicle

dark

eumelanin

pheomelanin

light

guard hairs

stiff hairs that make up outer coat of animals

buckling

what does pubic hair do that is different from head hair

postmortem banding

if a hair was obtained from a deceased person, it may exhibit this

trilobal, hollow, circular

3 common synthetic fiber shapes

human v animal, part of body, race, disease, forced removal, chemicals

what conclusions can be drawn from hair analysis?

climate, organisms, relief, parent material, time

soil forming factors

O horizon

organic material soil

A horizon

top soil

E horizon

elluvial layer

B horizon

subsoil

C horizon

parent material

R horizon

bedrock layer

hue, value, chroma

the Munsell color book looks at these for soil analysis

value

measure of lightness or darkness of the color 0-10

chroma

strength of soil color

sieve designation

as the mesh size increases, the opening in the sieve gets smaller

mechanical, chemical, thermal, electrical, optical

physical properties of glass

pigment, binder, solvent

what is paint composed of?

pretreatment

electrocoat primer / e-coat. coating of zinc phosphate applied to the steel body of the vehicle to prevents rust and corrosion resistance; colors range from black to grey. The electrocoating is a resin/binder/pigment blend

type, size, # of samples

type of techniques chosen for paint examination depends on these