An approach to the impact of nanoscale vat coloration of cotton on reducing agent account

► Nanoscale vat dyes with particle sizes ∼20 nm were successfully prepared. ► Pigmentation of vat dyes was carried out producing a new crystal form. ► The ball milling and chemical structure of dyes were influential. ► The nanosize vat color exhausted on cotton more than the conventional one. ► The nanosize vat colors can behave as a leuco form in absence of reducing agent. ► This focus reflects on environmental concern with respect to reducing agent.