Any is the transparent drawing technique and "optics ash" The transparent drawing technique is on the known frame the drawing most ancient drawing technique, most early may trace to 15 centuries. It was 19th century before European tradition drawing technique. The transparent drawing technique mainly is carries on the color cover to dye, causes two kind of colors well distributed to have the third kind of color through the vision, it although has the same appearance with the physical well distributed derivation third kind of color, but the visual effect is dissimilar, former is deeper, has the jewelry gloss. Makes in the picture process in the utilization transparent drawing technique, picture sketch relations are in do not use the color in the situation to complete. So-called does not use the color, refers is determines by the monochromatic high-sounding talk form the composition and the physical image volume feeling. Then, or ?? the color increases the color by the transparent thin color. The transparent drawing technique includes: (1) passes ?? reveals again. Generally with does not adjust the powder in the background and main body dark or little adjusts the powder the greasepaint to carry on the multilayer to cover the color, the disclosure woven and the bottom color. (2) thin bottom transparent cover color. Draws the stricter plain-colored oil painting in on the middle melody ash brown bottom with the deep brown or the silver-gray color, after treats does coats thoroughly ??, passes ?? avoids excessively calling in the white, in order to avoid influence transparency. Therefore, the bottom picture plain-colored oil painting needs to enhance the brilliance in advance, is the multilayer covers the color to leave behind the leeway. (3) thick bottom transparent cover color. Refers thick spreads the smooth surface and the bottom picture in the bottom picture thick spreads the concave-convex superficial upper hood to pass ??. Thick spreads the smooth surface to refer first uses the thick color to treat has not done time puts down, after does covers thoroughly ??. This law multipurpose to classical wind oil painting. For example the flesh are been partial multipurpose the light thick spreads the pigment, causes it with the background and so on dark color partial thickness to spread out. Thick spreads the pigment has not done when with the writing brush gently sweeps the uniform brushwork to carry on smooth processing, after does thoroughly covers again thoroughly ??, can achieve both is thick and the transparent crystal clear effect. "Optics ash" is one kind of visual effect which the transparent drawing technique displays. Ancient times the artist cultivated in Tanzania pulls or on the oil ?? bottom ?? carries on the glaze after the resin to dye, spread by is transparent or the translucent overburden layer, caused the assorted level through overlap to be revealed, namely had the color strange transparent gray ??"optics ash". This kind of transparent gray and mixes the gray compares, the visual effect is not greatly same. It is the direct drawing technique is unable to achieve. Reubens on created optics ash to be famous at that time, he once said to his student: "At least the dark final level color should be transparent." Like chart 29 is Reubens's oil painting part