[Ian101]

Just done a nice patio / drive job ... drive no issue but on patio which is indian stone there were a lot of black spots so following advice on my hypo post last week i tried solution of 3 to 1 and let it dwell for 10 minutes and in fairness like magic 99% of it was gone however along edges of flags were black spots that just wouldnt shift even with 100 % undiluted hypo for 10 minutes then pressure wash they still wouldnt shift so told customer all i could do was turbo nozzle em but more than likely all the pointing would go so he said just leave it as was happy with overall standard but I wanted it all gone.

Anything else I could have done

[Kev Martin]

Just done a nice patio / drive job ... drive no issue but on patio which is indian stone there were a lot of black spots so following advice on my hypo post last week i tried solution of 3 to 1 and let it dwell for 10 minutes and in fairness like magic 99% of it was gone however along edges of flags were black spots that just wouldnt shift even with 100 % undiluted hypo for 10 minutes then pressure wash they still wouldnt shift so told customer all i could do was turbo nozzle em but more than likely all the pointing would go so he said just leave it as was happy with overall standard but I wanted it all gone.

Anything else I could have done

Yes you could try Honing Powder then you would have had a mechanical cleaning action as well as the chemical action


Kev Martin
Tiling Logistics

[Roger Oakley]

Maybe a longer dwell time say 20-30 minutes, I know what you mean about the ones along the edges being stubborn had them myself a couple of times and had to leave the hypo of for around 1 hour keeping it damp so it works. Sometimes they are easy, and sometimes a pain in the arse.

[Barry W]

Whats Hypo as I've got these spots in my garden and the pressure washer does not get rid of them, someone told me to put diluted bleach on them.

[Neil Jones]

You answered your own question Barry. Sodium hypocholrite - Hypo - AKA Bleach.