Clean mortar from indian sandstone - Problems after pointing

[rawdon51]

Hi - wonder if anyone can help. We now have some very unsightly Raj Green flags after the builder left the patio uncovered after he'd pointed and it rained. The colour is greyed & washed out, with unsightly mortar "splodges" around the joints. Is there any way to clean the flags?

Many thanks for your help.

*** Links to pictures below.....hope they work....please let me know if not as I've never posted on here before ***

Patio Picture 1

Patio Picture 2

[lutonlagerlout]

oh dear and it wasnt a big area to cover either
pre wet the area then use hydrochloric acid
try a small piece of off cut first as some stones can react with the acid
clean a flag or two then wash off with clean water
wear all PPE
this means goggles gloves etc
its dangerous stuff
alternatively you could try jet washing but i fear the staining is too bad
LLL

[rawdon51]

Thanks LLL. I think you're right about the jet wash - the builder tried it and didn't seem to make it any better. Just another idea - the paving actually looks lovely in the wet as the colours change dramatically and the white-grey mortar virtually disappears (...or maybe goes dark grey-black and is not unpleasant). Not too much a fan of "wet look" sealants, but would something like this or a colour intensifier perhaps change the look to something more pleasant permanently?

[local patios and driveway]

Nope, it needs to be cleaned off to look right. No short cuts im afraid. Other options are wire brush (lots of time) or sandblaster gun. Think i would get the contratcor back and sit back and watch him sort it out.

[rawdon51]

Thought as much. OK, thanks for the advice.

[Tony McC]

That looks like Fissile Mint - DO NOT use an acid based cleaner: it'll make it all go rusty.

I know it can be hard to believe that Fissile Mint could be any worse, but daubing it with acid is a sure-fire way to completely bugger it. On some light cement stains, Lithofin MN Power-Clean has been known to help, but it's not guaranteed because it's alkaline based.

Time and weather are the best cleaners, but sand/grit blasting is also helpful.

And as others have said, I would be wanting the eejit contractor to pay for all this....

[rawdon51]

Thanks Tony, and thanks for your excellent site - although this is our first post, it's a constant source of useful information. Mrs Rawdon51 is currently spending her days with wire brush / chisel (for big bits), and is managing to have a positive effect on the look of the patio.