Removing stain from exterior wall caused by central heating discharge

[deadshort]

Hi, can anybody advise on the best method of removing a stain caused by the discharge of my central heating system pipe down an exterior shingle wall ? It looks unsightly like rust !

Thanks in advance.

DS

 

[Agile]

Best to ensure that immediately it discharges the problem is fixed. Then it can be quickly washed off.

My suggestion is to brush warm citric acid solution on the stains. But with correct precautions for handling acids!

Tony

 

[deadshort]

Thanks Tony. I will try a pressure washer first.

DS

 

[Agile]

I don't expect that will have much effect.

Iron oxides are very good at staining.

Oxalic acid is expensive but good at dissolving iron oxides but cost too much for large scale application.

 

[DP]

Blast from the pressure washer may well be the way to go first. Costs you nothing with that approach

 

[deadshort]

Thanks chaps.

It has had some effect i'll just keep at it with the PW.

DS

 

[Jackrae]

Oxalic is great for removing rust stains and isn't expensive if you buy the crystals and make up your own solution. 2.5kg for less than £15 from fleabay. Mix some up with warm water to dissolve crystals and brush on - leave for a few hours and then wash off
Download the MSDS sheet, read it and exercise suitable care.