This work deals with red organic dyes identification using molecular spectroscopic method. The infrared spectroscopy in reflectance mode (wavenumber between 650 – 4000 cm-1) has been optimized for identification of nine selected red dyes (i.e., akaroid, brazil, dragon blood, kamala, logwood, cochinea, kraplak, lac and santal).
The spectra of individual dyes and their main dyeing components were measured. The significant absorption bands of individual dyes were found and used for identification and differentiation of studied dyes.
Further the model samples of dyed textile fibres were prepared. The wool and viscose fibres were mordanted by three types of mordants (namely potassium aluminium sulphate, ferrous sulphate and cupric sulphate) and dyed with seven dyes.
The spectra of dyed textile fibres were measured both before and after an accelerated ageing by emission in visible and near infrared area. The ageing had no influence on the dyes, but the fibres were degradated.