Abstract: In this article, tussah silk fabric was treated with p-hydroxybenzaldehyde and nitric acid in order to achieve the purpose of dye-free coloration. Through orthogonal experiments and single factor analysis, the optimum process of dye-free coloration were, p-hydroxybenzaldehyde 5%(o.w.f.), nitric acid 2.5%, temperature 90℃, time 60min and bath ratio 1:30. Meanwhile, color fastness test and breaking strength test were taken, the results showed that, the color of tussah silk fabric after dye-free coloration was bright, the levelness was good, the surface of the fiber was almost no damage, both rubbing fastness and washing fastness were reached 4 grade or above and no significant change were shown in breaking strength.

Key words: Hydroxybenzaldehyde , nitric acid , tussah silk , dye-free , coloration