There is only one way – to painstakingly remove them by hand. Or perhaps run germination trials to determine the effect because it might not make a difference :-)

Dear Saeid, 

seed cleaning of Nigella sativa is usually without difficulty. I am quite surprised...

Bozena

Dear Bozena

we use some usual apparatus to  clean seeds( similar to other kind of seed), but finally we have a lot of sifting. wind, gravity, ..... not any results.

Dear Saeid

Hi, just to let you know that I am not expert in this issue. i may refer you to the Gene bank of RIFR and Dr Salehi the head of this division

Do you mean more than threshing and winnowing? If you do not mean with modern methods, you can spread the capsules on canvas in sun and thresh when dry and you can use wind for separating the black seeds from other waste materials. Thank you! 

hi and thanks

we have problem by using modern methods. some thing is wrong.