[Ged]

Hi
Has anyone got any bright ideas as to how to clean concrete paving slabs,the sort that have a pattern on them. the grime seems to be embedded in the fabric of the slab and won't budge, i suspect a chemical change has taken place and the staining is  not just surface or trapped dirt. I've tried to pressure wash them at 250 bar with a lance and a flat surface cleaner but to no avail. maybe a chemical is needed, i just don't know, maybe yoo doo

cheers 
               Ged

[Alex]

Try and very small area with brick acid leave for 5 minutes or so and then wash off - do you have any pictures?

Alex

[Ged]

Sorry no pics. i've never heard of brick acid but will look into it

ged

[martin19842]

hi there,

yes try a brick acid 17.5% hyrdrocloric scrubbed in, and then rinsed out, be careful the acid could take the face off the concrete, however if they are already 'beyond repair' then nothing to loose really.

regards

martin

[Ged]

Thanks for that Martin, who sells brick acid ? would it be a builders merchant or cleaning materials supplier ....

Ged

[martin19842]

hi there,

both sources, however, cleaning supplies can generally get a hgher concentration if required.

regards

martin

[Alex]

Make sure you wear protective equipment as I spilt a little on my finger and it ate my nail - had to go to hospital and get some gel - however, the stuff I use is 33%

Alex

[martin19842]

hi there,

i just try to avoid the 33% stuff, its a bit horrible.

regards

martin

[Len Gribble]

Care when using any type of cleaning agents you may wear ppe the plaints don’t some don’t even in a diluted form.

Len