I had the external walls repointed with a cement/lime mortar (5:1:1 I think). Generally OK but several 'overruns' and mortar splashes, especially in the windows reveals. I've tried washing down with water and a wire brush, but it's slow going and doesn't completely remove the mortar
Any top tips to clean up the bricks?
I suspect that brick acid will do it, but I'm not sure you want that anywhere near window reveals.
You can mount a wire brush on an angle grinder, but I don't think that's safe to use from a ladder. Not that brick acid is particularly safe, either.
Definitely, apply with a stubby brush, let it 'fizz' then wash off ...
Yeah. brush with hydrochloric acid (brick acid), leave an hour , and pressure wash. Or just hose down.
Repeat until satisfactory
It's not too bad. have a bowl of water and a sponge ready to dilute any splashes on self clothes or windows down to safe levels.
Wear safety squints if possible.
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Hydrochloric acid AKA Sprit of salts.
Just a warning that brick acid doesn't work (or is much less effective) on mortar that has SBR admix. I wish I'd been more careful repointing our crazy paving patio.
Thanks all - some variant of hydrochloric acid it is then. There's quite a range of strengths, between 5% and 20%. I'll look for something in the middle.
I'm not sure if was washing off anyway, but a 50/50 solution of vinegar seems to have got the worst of it off one test section.
Yes, that does work, but its an expensive way to descale. Citric acid sold as appliance descaler is a bio-safe alternative but brick acid just fizzes it all away.
pH 1 is acid, pH 7 is neutral, pH 14 is base.
"Acetic acid is a weak monoprotic acid"
Each is in a different class in a sense.
And that would be in the rough order they "attack" the good material.
How they neutralize, is graphed here. At least one of the tri-protics has a nice signature curve.
Paul
What does the x-axis % represent?
I'm also not sure that the statement "Sulfuric acid - while its second proton is much less acidic than the first one - is strong enough so that both protons get titrated together." is correct. Salts such as sodium hydrogen sulfate are well known. They exist because only one proton is neutralised and the NaHSO4 itself is still very acidic. Mind you, it's well over 60 years since I did this stuff, so ICBW...
Lawns hate dog pee, but I wouldn't use that to clean a paintbrush... ;-)
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