Drawing materials studied by THz spectroscopy

TL;DR

This study applies THz time-domain spectroscopy to analyze various dry and wet drawing inks, demonstrating its potential to identify inks based on their unique spectroscopic features and measure their optical properties.

Contribution

The paper introduces an improved THz spectroscopic method for analyzing drawing inks, including layered samples, and highlights its capability to recognize inks by their spectral signatures.

Findings

THz spectroscopy can distinguish different drawing inks.

The technique accurately measures optical parameters and thicknesses.

Spectroscopic features are unique to each ink type.

Abstract

THz time-domain spectroscopy in transmission mode was applied to study dry and wet drawing inks. In specific, cochineal-, indigo- and iron-gall based inks have been investigated; some prepared following ancient recipes and others by using synthetic materials. The THz investigations have been realized on both pellet samples, made by dried inks blended with polyethylene powder, and layered inks, made by liquid deposition on polyethylene pellicles. We implemented an improved THz spectroscopic technique that enabled the measurement of the material optical parameters and thicknesses of the layered ink samples on absolute scale. This experimental investigation shows that the THz techniques have the potentiality to recognize drawing inks by their spectroscopic features.