论文部分内容阅读
土黄也是绘画常用的一种黄色颜料。只是它在其它方面的应用不及雌黄。土黄,又名“黄赭石”。和赭石一样,同是含三氧化二铁的土性天然矿物,不同的是黄色含铁矿物含有结晶水,而赭石则无。土黄一般为针铁矿晶形,其化学组成主要是α羟基氧化铁(α-FeOOH),从矿物学上看,是颜色纯净、结构松软的褐铁矿变体,并含有大量的粘土、白垩,有的还存在三氧化二铁、四氧化三铁或氧化锰等多种杂质。因此,土黄颜料的颜色在纯黄到暗黄、暗棕甚至棕红色之间变化,水合三氧化二铁的含量越高,杂质含量又愈低的,颜料的质量、颜色愈好。土黄颜色的浓淡与羟基氧化铁的含量有关,例如:含12—25%时为浅黄色,25—40%为正黄色,40
Yellow is also commonly used in painting a yellow pigment. But it is less than other applications of female yellow. Earth yellow, also known as “yellow ocher”. Like ocher, it is a native earth mineral containing ferric oxide, except that the yellow iron-bearing mineral contains water of crystallization, whereas ocher does not. The yellowish goethite is generally of the goethite crystal form and its chemical composition is predominantly α-iron oxyhydroxide (α-FeOOH). Mineralogically, it is a pure, soft-textured limonite variant with lots of clay, chalk, Some still exist ferric oxide, ferric oxide or manganese oxide and other impurities. Therefore, the color of khaki pigments vary from pure yellow to dark yellow, dark brown or even brown red. The higher the content of hydrated ferric oxide, the lower the content of impurities, the better the quality and color of the pigment. The color of earthy yellow is related to the content of iron oxyhydroxide. For example, it contains light yellow when 12-25%, positive yellow 40-40%