Max Frei theory revisitation: does really strokes depth change along time?

Area of Science:

• Forensic Science
• Document Examination
• Material Science

Background:

• Establishing the age of written documents is crucial in questioned document examination.
• The Max Frei theory proposed that ink stroke depth changes over time, enabling document dating.
• Previous methods relied solely on microscope analysis to assess stroke depth.

Purpose of the Study:

• To investigate the validity of the Max Frei theory for dating documents.
• To analyze the influence of time and microclimatic variations on ink stroke depth.
• To determine if 3D stroke profile analysis can accurately date handwritten documents.

Main Methods:

• Utilized a laser profilometer to measure ink stroke depth.
• Examined stroke depth stability over time under controlled environmental conditions.
• Assessed the impact of humidity variations on the 3D stroke profile.

Main Results:

• Ink stroke depth remained stable over time when temperature and humidity were constant.
• Humidity variations caused a non-linear reduction in stroke depth, exhibiting hysteresis.
• The 3D stroke profile analysis proved incapable of determining document age.

Conclusions:

• The Max Frei theory's premise of time-dependent stroke depth changes is not supported by empirical evidence.
• Microclimatic factors, particularly humidity, significantly alter stroke depth but do not correlate with document age.
• 3D stroke profile analysis is not a viable method for dating questioned documents.