Investigating the Performance of NIR Spectrometry for Identifying Madder as a Natural Dye from Synthetic Dyes Used in Handmade Carpet

Gorji, S.; Gharanjig, K.

Investigating the Performance of NIR Spectrometry for Identifying Madder as a Natural Dye from Synthetic Dyes Used in Handmade Carpet

Authors

S. Gorji ¹
K. Gharanjig ²

¹ Department of polymer engineering and color technology, Amirkabir university of technology

² Department of Organic Colorants;Center of Excellence for Color science and Technology, Institute for Color Science and Technology

Abstract

Due to the difference between price and value of natural versus synthetic dyes, it has always been very important to distinguish these two categories for handmade carpet. This study aimed to investigate Near-IR spectrometry technique to identify natural madder and synthetic dyes used in handmade carpets. To do this woolen samples with two major races (Baluchi and Kermanshahi) were dyed with madder dye with alum and tin chloride mordant, and also synthetic dyes to provide conventional red-colored shades. The 60 dyed samples including of 24 madder, a set of 10 mixed (combination of Madder and synthetic dyes), 26 synthetic dyes, and 5 cases gotten from carpet, and in total 65 samples were prepared. Results showed that the spectral reflectance of the madder samples has an increasing slope in NIR region while the NIR spectral reflectance of synthetic dyes does not show any noticeable increasing trend. Considering the obtained results of this research, NIR spectrometry can be a feasible method to distingush between madder and synthetic dyes and it was quiet possible for the test samples with almost no errors. However, investigating on more samples would be suggested. Note that it is not possible to detect samples dyed with a mixture of madder and synthetic dyes. The mixed samples were presented in one of the two groups; synthetic or madder.

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