concrete stains

[Franky]

layed some black bricks on driveway and have some concrete splashes and stains on some. any way of removimg these ?

[Andrew Mawson]

Acid brick cleaner then a pressure washer.

As the bricks are black I'd buy drain cleaner which is 95% sulphuric acid as it's cheaper but not clear so no use on light backgrounds. Dilute 1:3 (remember 'do what you aughter - add the acid to the water') and apply with a plastic brush whilst wearing old clothes, rubber gloves and welly boots. When the stains stop fizzing add more acid till they're gone and then hose everything down with liberal quantities of water. (If you have a pressure washer the thinner bits will come off with that).

When you're done peel off ALL your clothes directly into the washing machine and give them a good wash or you'll end up with holes in everything.

(I recently built a garage with a gable end, and we had a downpour just as I finished the gable - mortar was washed down the bricks bigtime. The above process worked very well)

Andrew Mawson

[The Natural Philosopher]

Brick or patio acid and a wire brush.

[The Natural Philosopher]

I use it neat.

I have several pairs of jeans available for precisily this kind of work. After you have wiped paintbrushes on then, dropped CA adhesive on them, used them to wipe the nixzzles of various sealants and glue guns, and wiped a soldering ron on them a few times, holes only add to the effect.

It does. Th acid dissloves te cement bonds, and teh wire brush loosesm the aggrefate and teh water washes it all away...

[Michael Mcneil]

It's caustic soda shirley!

Sulphuric acid is not the best thing to dissolve lime rich products. Why environmentalists insist it causes damage to portland stone is beyond me. Brick cleaner is hydrochloric acid and readily dissolves calcites.