Brick dust out of vertical blinds

[New2adultlife]

Hi all ,
My house has just been rewire and stupidly I forgot to take the WHITE vertical blinds down they are full of brick dust .
What’s the best way to wash them without the brick dust staining them . I’m so worried now I can’t afford to replace them !

I had a similar issue recently. I have those fabric tapes running down so I really wanted to avoid staining them! I closed them and sort of brushed all the excess off with a feather duster. Then basically had to painstakingly wipe each slat. There are probably better ways!

Lots of people say dip them in the bath? But mine don't come down easily.