Formulations of primer, acrylic paint and pastel in traditional Thai style colour

Abstract

This research aimed to improve Thai traditional primer, used for mural painting, with antibacterial property, to formulate novel primers having antibacterial behavior, scrub resistance and washability as well as to formulate paints according to Thai color dictionary. Both primers and paints were aimed to use in mural painting. We divided the research into 3 parts: 1) improved traditional primer and formulated novel primer with antibacterial, washable and scrub resistance properties; 2) formulated acrylic paints and pastels according to Thai color dictionary and 3) investigated the wavelengths used for distinguishing the change of paint caused by light, moist and heat using multi-spectrum imaging technique. Traditional primers that were made of natural constituents particularly tamarind glue and white clay hardly resist to environmental factors including the microorganisms because the natural components encourage their growth. Titanium dioxide, TiO2, and silver nanoparticles, AgNPs having antibacterial property, were used in the formulations. Subsequently they were tested against 4 bacterial species; Bacillus subtilis, B. cereus, B. mycoides, and Leclercia adecarboxylata that were found on the mural painting surface of Somanas Rajavaravihara temple in Bangkok, Thailand. The presence of TiO2 and AgNPs in the novel primers inhibited the growth of these 4 bacteria, while neither the traditional primer with AgNPs nor the one without showed inhibition activity against all 4 bacterial species. On the other hand, the novel formulated primers containing TiO2, aluminum silicates and AgNPs showed the best inhibition and the second best was the primer with aluminum silicates and AgNPs. The latter gave better scrub resistance and washability than the former. Primary colours were formulated, 11 colours for acrylic paint and 12 colours for pastel. These primary colours were used as database to formulate traditional Thai style colour for acrylic paint and pastel respectively. Samples of traditional Thai style colour were made, twenty colours for acrylic paint and forty colours for pastel. The color differences CIEDE2000 between the formulated and the Thai color dictionary’s CIELAB values were less than 3. The pass-fail color tolerance and brush testing were carried out by Thai artists. In addition, multi-spectrum imaging technique was employed to study the spectroscopic characterization of paints, pastel and primers that were influenced by changing of moist, heat and UV radiation.