Colorants Flashcards
What type of paint evidence is most commonly examined in hit-and-run cases?
Automotive paint is the most common type of paint examined in hit-and-run cases.
What are the typical layers of automotive paint?
- Electrocoat primer (for corrosion resistance),
- Primer-surfacer (to smooth out imperfections),
- Basecoat (the actual color of the vehicle),
- Clearcoat (unpigmented layer for gloss and durability).
How should paint evidence be collected in a hit-and-run case?
Paint evidence should be collected by scraping uncontaminated paint from an undamaged area of the vehicle using a clean scalpel or knife. Samples should go all the way to the bare metal.
What is the significance of collecting reference paint samples in hit-and-run cases?
Reference paint samples are collected to compare with paint transferred to the victim or another object, helping to determine if the suspect vehicle was involved in the incident.
What is the key difference between dye-based and pigment-based inks?
Dye-based inks are water-soluble and tend to be more vibrant but less lightfast, while pigment-based inks are water-insoluble, more stable, and longer-lasting.
What are some methods for analyzing ink?
- Non- destructive
- UV light examination,
- Fluorescent light examination,
- Infrared light examination. - Destructive
- Paper chromatography,
- Thin layer chromatography (TLC),
- High-performance liquid chromatography (HPLC).
How can thin layer chromatography (TLC) be used in ink analysis?
TLC is used to separate and identify colorants in ink. It can compare questioned inks to known standards to determine if they are the same or different.
Why is aging an important aspect of forensic ink analysis?
Aging is important because if an old document has been altered recently, the newer ink will have a different composition than the old, aged ink, which can be detected through appropriate techniques.
What are some common types of document forgery?
- Signature forgery,
- Alteration of dates or amounts,
- Counterfeiting of official documents (e.g., passports, checks).
What are some methods used to detect document forgery?
- Handwriting analysis,
- Ink analysis (e.g., chromatography, UV light),
- Paper analysis (e.g., watermarks, fiber composition).
What is the role of ink analysis in detecting document forgery?
Ink analysis can determine if different inks were used on a document, which may indicate alterations or additions. It can also help identify the type of pen used and the age of the ink.
How can UV light be used to detect document forgery?
UV light can reveal differences in ink fluorescence, which may indicate that different inks were used or that parts of the document were altered.
What is the significance of handwriting analysis in document forgery cases?
Handwriting analysis can determine if a signature or text was written by the same person or if it was forged by comparing characteristics such as stroke direction, pressure, and letter formation.
How can paint chips help identify a vehicle in a hit-and-run case?
Paint chips can be analyzed to determine the make, model, and year of a vehicle by comparing the paint layers and chemical composition to databases like PDQ.
How can ink dating be used to detect document forgery?
Ink dating can determine the age of ink on a document. If the ink is newer than the document’s supposed age, it indicates that the document has been altered or forged.
