Odd stains on render

[Lee Nowell]

Hi all,

We have jet washed the rendered walls around the patio ready to finally paint them. They seems to have some staining on them but not sure what it is. I have uploaded a photo here

Anyone have any ideas what it is and more importantly whether I should just paint over it? If not, any ideas how to get rid of it?

Many thanks

Lee.

[The Natural Philosopher]

Looks like efflorescence to me. I.e there are bricks underneath that are leaching out salts.

try wishing with dilute acid to see if you can remove most of it. But even so I fear that if you paint it now,it wont stick very well. If it is effloresence, a winter of rain should fix it.

Can you wait till next year?

[Brian Gaff]

Obviously I cannot see it, but the last time I had wallcote put on, they went over the render with a small wooden mallet listening for hollows where the render was blown and replaced it then sealed the joints between old and news until the whole lot looked a bit like camouflage with rivers on it. Some drying then a coat of some undercoat that smelled of rotting grass, but that might be my nose, and then the top cote was sprayed on using a hand held sprayer masking windows and doors of course. Its been on for over

15 years now and still apparently looks fine. I So I guess it all depends on what you are covering it with. Traditional paint will probably let the marks show through, but that depends very much on the colour you choose. Brian

[Lee Nowell]

Thanks very much both. Yes could well be that as that area is brick (the rest is block). I could wait to paint it (although not ideal) but the tender has been unpainted for years so assume if the rain would sort it out it would have done so by now?

In terms of paint Brian then we were going to use outdoor masonry paint.

[The Natural Philosopher]

Well if you can pressure wash off the loose stuff waiy for it to dry and paint it.