Stained red brick

[seasickstevie]

What's the way to get black stains, caused by a century of coal fires and acid rain, out of red brick.

I've tried brick-cleaning acid, but that makes virtually no difference (although it does remove excess cement from brick face etc.)
And I've scrubbed with bleach. Again little difference.

Perhaps I need to sandblast. Just that I feel that will damage the surface.

Is their a technique I've not discovered?

I know taking sections of brick out, and turning them around works brilliantly, but life's too short!

 

[kiwiRich]

Try some hydrochloric acid bro. We have used it in the past to get pavelock silocone off cobbles. Dont forget your gloves though.
Otherwise you may find your only option is to spin the buggers round. Red clay bricks tend to absorb surface colours pretty quick with only a little moisture in the air so I wouldnt be surprised if the staining went quite deep