The major material for their paintings consisted of metal oxides, iron oxide being the most commonly used. The use of metal oxides could produce red, blue, and yellow colors, and if heated, the colors would multiply.
化學家分析他們作畫的顏料，主要來源是金屬氧化物，其中又以鐵的氧化物最常用，它能產生紅、藍、黃等顏色，若經加熱，則色彩可更豐富。