Brick acid damaged my wall?

[needsomehelp]

Hi -

I spent Saturday trying to clean mortar from external brickwork after a bad repointing job by a builder a few years ago. I used brick acid to clean the wall, and washed it down thoroughly after 20 minutes with water.

Now, though, the section of wall I applied the acid to looks darker - almost as if it's damp. Has the brick acid damaged the wall, or is it just that the wall hasn't fully dried yet?

Other areas of the wall that also got wet when I rinsed off the acid do not have this damp appearance, but I wondered whether the acid might cause that section of wall to dry more slowly?

I'm worried that I might have permanently discoloured the wall now

 

[^woody^]

The acid attacks the cement and not the clay brick.

20 minutes is a long time to leave the acid eating into the mortar - has it gone sandy? You should really wash it off within a few minutes. But if the brick faces where exceptionally smudged, then it may well dry with differing shades.

You did dilute it and wet the whole wall first didn't you?

 

[Richard C]

Te acid will have removed the weathering effect on the surface of the bricks so it’s quiet likely the area you treated will look darker now, more like the bricks looked when they were new. It’s unlikely you will damage the bricks as the acid attacks the relatively soft mortar far more easily (as has already been said); after all, that’s what it’s supposed to be doing!

You could try washing the rest of the wall with an industrial pressure washer - not the cheap DIY ones as they don’t develop sufficient pressure - but avoid directly blasting the mortar joints. Personally, I would have tried this in the first place (it worked a treat on mine) before resorting to chemicals; they are never really a good idea & if you do use them, you shouldn’t blanket treat the wall only the surface of the bricks that have mortar on them, otherwise the acid will also eat away at the mortar joints!

 

[needsomehelp]

Thanks for the suggestions and advice so far - much appreciated.

When I arrived home last night, I noticed the dark areas had faded and were a much better match for the rest of the wall.

However, this morning, they were dark again, so I'm sure that the wall is now absorbing more moisture in the areas where I applied the acid (there was quite a lot of dew this morning.....).

So I guess my question now is: Is the acid likely to have made the wall more absorbent by damaging the surface (sounds like it probably hasn't from the answers above)?

Or do I just need to wait for the wall to dry out properly and for any acid residue to be washed away by the rain over time?

P.S. In reply to woody - I didn't wet the wall first, as the instructions didn't say to do so - I bought the brick cleaner from B&Q, so I'm not sure it's particularly strong. I double-checked the bottle this morning, and there is no mention of wetting the wall first.

Thanks!