STAINED SLABS !!

Have a bit of a problem and wonder if anyone has come across the same thing on a small slab repointing job.

On a natural stone slab we have cleaned of dried cement mortar left from earlier pointing with Wicks brick acid. We have then repointed with portland cement and building sand applied as a semi-dry mix.

Left the job thinking all was well.....5 days later customers let me know that brown stains had appeared on 5 or 6 of the slabs.

Have tried to remove stain with brick acid (which I appreciate might have been the original culprit). Although a slight improvement the stains are still there.

Any ideas anyone??

you shouldnt use brick acid on natural stone. its porus and will discolour with it. You wont be able to get rid of it. Sorry its a bit after the horse has bolted!

one of the best ways i find to remove mortar stains from a natural product or brick, is to rub it with a piece of the same stone/brick.

Thermo said:

you shouldnt use brick acid on natural stone. its porus and will discolour with it. You wont be able to get rid of it. Sorry its a bit after the horse has bolted!

one of the best ways i find to remove mortar stains from a natural product or brick, is to rub it with a piece of the same stone/brick.

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Thanks for that Thermo................pity they never thought to mention it on the tin!!