There is no given rules to be followed for gouache by painting knife. Each individual can try, practise, study and create in the most free way of his own will.

水粉画画刀技法无古法可循，尽可根据个人愿望，以最自由的方式去尝试、实验、研究和创造。

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This technique is often used in oil painting, where the different coloured paints are applied directly to the canvas with a palette knife.

这种技术通常用于油画，其中不同颜色的油漆是直接用调色刀涂在画布上。

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Batik is a traditional Chinese folk art which combines painting and dyeing. it is made by dipping a special knife into melted wax and paining various patterns on pieces of white cloth.

蜡染是中国传统民间艺术，它综合了绘画和染色工艺。蜡染的主要方法是用蜡刀蘸蜡液，在白布上描绘图案。

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"If it was an angry young man like Amitabh Bachchan (Bollywood acting legend who rose to fame in the 1970s), they would paint his face red with anger and they would use techniques like painting over the canvas with a knife to give him a more rugged, macho look, " Jethwani explained.

CNN: Bollywood poster painters face extinction in digital age

He played the publicity game with aplomb, convincing interviewers that he had been in rather more fistfights than he had, and that his hobby was knife-throwing. (It was painting.) He bought a horse farm in Vermont and a mansion in Bel-Air.

ECONOMIST: Charles Bronson

Lucy, in a late painting, is not her lover but her executioner, pressing a knife to her bosom.

WSJ: More than a Mere Colorist | Veronese | Ringling Museum of Art