There is an easy fix for this problem.
Buy some electro cleaner, spray it on the break dust and use a brush to remove the dust.
In my example iv used ELECTRA CLEAN Spray, made by Rocol but maybe any Electronic cleaning spray will work:
As i understand it electro cleaners are flammable, so maybe it is best to avoid getting this stuff on your breaks, since they can get very warm.
Step 1- This is the stuff needed:
Step 2 - Spray on the Electro Cleaner and brush as long as needed
Step 3 - Clean with water and enjoy the result