Answer:
(Fatwa: 2011/1626/B=1432)
A burqa does not get impure by colouring it from blue to black colour. However if you wash it as precaution then it is good. You can wear it after washing it thrice.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband
