The materials and techniques employed in 18th to 20th century art works from Thailand have received little attention compared to those of other Asian countries, most notably China and Japan. A multi-disciplinary study of Thai manuscripts and banner paintings aims to characterize the materials used, inorganic and organic pigments and binders, and the painting techniques employed. Samples from these works have been analyzed by a range of techniques, including x-ray flourescence (XRF), Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive microanalysis (SEM-EDS). The results suggest a change in palette from the 18th to 20th century due to the introduction of imported pigments, most notably emerald green, Prussian blue and chrome yellow, during the 19th and early 20th century. The analyses show that the green pigment used on most 18th century manuscripts is an organic copper salt, a hydrated copper citrate, which has not previously been identified on art works. The occurrence of this on a number of different art works suggests deliberate manufacture of this unusual pigment. The color of the copper citrates differs depending on their hydration state and they are easily dehydrated and re-hydrated. This suggests some alteration of the original manuscript pigments might be expected, raising questions as to the original color of the pigment and whether the visual appearance has altered with time. In order to assess this, the pigments found on the art works must be fully characterized and any variations identified. The study includes laboratory based sythesis with pure reagents and synthesis following a recipe for refinement of verdigris given in a 17th century Venetian manuscript.