Is Xuan paper the sandpaper for civil contract writing?

no.

Xuan paper is mainly used for writing China traditional calligraphy and drawing traditional Chinese painting, and can also be used for printing, painting and calligraphy mounting, arts and crafts gift packaging and other purposes.

Xuan paper has good ink wetting property, strong durability and aging resistance, and is not easy to change color. Xuan paper is tough and moist, smooth but not slippery, white and dense, pure in texture, lossless in rubbing and strong in ink wetting, and has unique permeability and lubricity. Writing and painting "five colors of ink" is completed in one stroke, with shades, visible textures, clear Mo Yun and distinct layers.