Chemical Studies on the Composition of Natural Paint Pigment Materials from the Kassena-Nankana District of the Upper East region of Ghana

Abstract

Three materials used in traditional paint making were analysed for their physical and chemical properties. Equipment employed were pH meter, AAS, Flame Photometer and X-ray diffractometer. The “kugsabla” has a density of 0.5, and is sparingly soluble in water. The “kugpela” has a density of 0.6, and is very sparingly soluble in water. The “zigmolgo” has a density of 0.46, and is sparingly soluble in water. Aqueous solutions of all the three materials were mild basic, having pH values of 7.98, 7.99 and 7.91 respectively. The X-ray diffraction results showed that the black pigment contained quartz, [SiO₂], Muscovite, [KA_l2(Si₃Al)O₁₀(OH)₂] and graphite, [C]; the white pigment contains Nimite, [(Ni,Mg,Al)₆(Si,Al)₄O₁₀(OH)₈], a nameless compound [Ni₃Si₄O₁₀(OH)₂], and Talc [Mg₃Si₄O₁₀(OH)₂], whilst the brown-red pigment contains hematite [Fe₂O₃] with 3 other peaks which could not be assigned – indicating also the presence of other substance(s). The “kugsabla” had an Iron content of 4440.754 mg/Kg. It also contains 211.939 mg/Kg of Lead, 233.214 mg/Kg of Magnesium and 39.428 mg/Kg of arsenic. The “kugpela” had 2802.065 mg/Kg Iron, 205.336 mg/Kg of Lead, 277.539 mg/Kg of Magnesium and the Arsenic content was 34.828 mg/Kg. The “zigmolgo” had 4886.976mg/Kg Iron content, 205.689mg/Kg of Lead, 15.569 mg/Kg of Magnesium and 36.244 mg/Kg Arsenic content. Zinc, Nickel, Calcium, and Potassium were also present in all the three pigments in amounts ranging from 55.988-107.057, 89.895-106.014, 50.150-342.011, and 25.473-871.275 mg/kg respectively.

Keywords: Paint, ochres, rocks, pigments, hematite